TL;DR
The Scrum Master's job is never "done." If you think the role has become unnecessary, you're likely overlooking something you should be doing or falling prey to the 100% utilization fallacy. Don't do that!
Your job is not to be busy all the time. Your job is to facilitate the process, and to be readily available and actively engaged with the team so that you maintain full situational awareness and remain fully plugged-in to the people and processes that affect the project. Even when it seems extraneous, the Scrum Master's job is to be immediately available for those times when the role is needed.
There's plenty to do, as you will see below. But being busy is not the same thing as providing value or being efficient!
Scrum Master Duties
The Scrum Guide devotes an entire section to explaining the ongoing duties of the Scrum Master. These include services provided on an ongoing basis to the Product Owner, Development Team, and the organization.
The Scrum Master is a servant-leader for the Scrum Team. The Scrum Master helps those outside the Scrum Team understand which of their interactions with the Scrum Team are helpful and which aren’t. The Scrum Master helps everyone change these interactions to maximize the value created by the Scrum Team.
Scrum Master Service to the Product Owner
The Scrum Master serves the Product Owner in several ways, including:
- Finding techniques for effective Product Backlog management;
- Helping the Scrum Team understand the need for clear and concise Product Backlog items;
- Understanding product planning in an empirical environment;
- Ensuring the Product Owner knows how to arrange the Product Backlog to maximize value;
- Understanding and practicing agility; and,
- Facilitating Scrum events as requested or needed.
Scrum Master Service to the Development Team
The Scrum Master serves the Development Team in several ways, including:
- Coaching the Development Team in self-organization and cross-functionality;
- Helping the Development Team to create high-value products;
- Removing impediments to the Development Team’s progress;
- Facilitating Scrum events as requested or needed; and,
- Coaching the Development Team in organizational environments in which Scrum is not yet fully adopted and understood.
Scrum Master Service to the Organization
The Scrum Master serves the organization in several ways, including:
- Leading and coaching the organization in its Scrum adoption;
- Planning Scrum implementations within the organization;
- Helping employees and stakeholders understand and enact Scrum and
empirical product development;
- Causing change that increases the productivity of the Scrum Team; and,
- Working with other Scrum Masters to increase the effectiveness of the application of Scrum in the organization.
Even on a smoothly-running project with a self-organized team, the chance that all meetings are self-facilitating, all present and future impediments have been rendered moot, and no further information about the project remains to be inspected, adapted, or radiated is essentially nil. So the need for a Scrum Master never truly goes away if you're doing Scrum properly.
Additional Scrum Master Duties
In addition to the core duties of the role, the Scrum Master has other functions as well.
The Scrum Master must work with the Product Owner, Development Team, and other involved parties to...[ensure] artifacts are completely transparent...[and] help everyone apply the most appropriate practices in the absence of complete transparency.
A Scrum Master... [detects] incomplete transparency by inspecting the artifacts, sensing patterns, listening closely to what is being said, and detecting differences between expected and real results.
The Scrum Master’s job is...to increase the transparency of the artifacts. This work usually involves learning, convincing, and change. Transparency doesn’t occur overnight, but is a path.
Only the Product Owner has the authority to cancel the Sprint, although he or she may do so under influence from...the Scrum Master.
The Scrum Master enforces the rule that only Development Team members participate in the Daily Scrum.
The Scrum Master also facilitates and enforces all the ceremonies and time boxes.
Reducing Project Communications Burdens
Furthermore, while not specifically called out in the Scrum Guide, the Scrum Master is often the Scrum Team member responsible for radiating information about the team and the project to the rest of the organization. This includes routine tasks such as:
- building burn-down charts
- working the stakeholders on release planning
- writing project reports
- monitoring or communicating project control metrics
and other things that organizations still expect from projects, even when they're agile. Since the Scrum Guide doesn't explicitly place these tasks on the shoulders of the Scrum Master it could theoretically be done by any team member, but the Scrum Master is ideally placed to handle it because:
- The Scrum Master is not bogged down in task delivery.
- The Scrum Master often has the bandwidth, especially later in a project's maturity.
- Taking the work on relieves the rest of the team of a non-delivery burden, which is the very essence of an effective Scrum Master.
If the Scrum Master didn't handle many of these tasks, they would eventually fall on someone else within the team. This would ultimately reduce team capacity, so trimming the "overhead" of Scrum Master slack would actually be a false economy.
The 100% Utilization Fallacy
[M]y team has now got to the point where outside of the initial sprint planning they are extremely self organised and do not need me for most days as a Scrum master since the planning is done very well at the start of the week.
Aside from the fact that there's clearly plenty for a Scrum Master to do (see the voluminous lists above), this question implicitly assumes the Scrum Master must be at 100% utilization to be valuable. This is simply the wrong way to look at any role on a cross-functional team.
The Scrum Master is part of the cross-functional team, providing skills of leadership, coaching, facilitation, process ownership and refereeing, problem resolution, and communications management beyond the specific activities define by the role. These skills are needed throughout the project lifecycle, and while they (hopefully) aren't needed every minute of every day, when they're needed they're often needed right then.
A Scrum Master with slack is routinely available for servant-leader and other tasks. A part-time Scrum Master, or one who is engaged in multiple parallel projects, is not immediately available to the team when needed most. This becomes a drag on overall project performance.
Scrum (and agile frameworks in general) embrace change, so the notion that because things are running smoothly now that they will always run smoothly is ridiculous. Projects change. Teams evolve. Team members leave, and new ones join. The organizational memory shifts, changes, and occasionally fails. So there's always something for a Scrum Master to do, and part of that job is simply to be available for those times when it's necessary.
"Being available" doesn't just mean having some holes in your schedule. It means always being actively engaged with the Development Team, the Product Owner, and the rest of the organization so that you don't have to "get up to speed" when challenges arise. Having to spin up for each new problem would be extremely inefficient! Remaining engaged, and maintaining the relationships and awareness necessary to resolve problems quickly is a often full-time job in itself.
Even when you don't have enough to do to remain busy all the time, get away from the 100% utilization fallacy. You don't have to be constantly buzzing like a bee to add value. Measure your value, not your level of busyness!
Of course, if you aren't adding any perceivable value, then you (just like other members of the team) can pull in additional work that adds value to the process, the team, or the organization. Just make sure that you aren't creating make-work; the goal must always be to support the process and the team, and pulling in excess or unnecessary work only makes it harder to remain focused on that objective.