Documentation is a Communication Aid
Where is information such as deviations to be documented?
There isn't a single answer for this, as it depends on what you're trying to document and the purpose of the communication. Deviations from a plan might even be documented in multiple places, and sometimes in different ways, depending on what you're trying to communicate and to whom. For example:
- Deviations that result in schedule risk probably belong on the Project Risk Log.
- Deviations that impact budget probably belong in an information radiator such as a bi-weekly budget report.
- Deviations that affect scope or quality should be communicated with stakeholders in whatever report or communications format project status is usually used to share with that group.
- Deviations that impact the project team, or (perhaps more importantly) downstream project teams or matrixed resources, should be shared through updates to start/stop or lead-time estimates, as these deviations may have a direct impact on their schedules, budgets, and estimates.
- Deviations that can be mitigated should be communicated through updates to the project plan.
- Deviations that can't be mitigated should be communicated to upper management for strategic decision-making.
The general theme of most of these items is effective communication. If there's a problem, be transparent about the nature and (if possible) the root cause of the problem so that the organization can take the appropriate steps to fix things, or at the very least not be surprised by sub-optimal outcomes if they are unavoidable. Burying the critical input needed for strategic decision-making is a sure path to project failure, so don't do that!
Note that some deviations are also simply an expected outcome of normal variance. If that's the case, these routine but acceptable deviations should be reported as such through the project's normal communication channels. A good project manager never covers up deviations from plan, but also doesn't cry wolf when such deviations are within acceptable tolerances and when the project plan has been properly built with sufficient slack to absorb expected variation.