I'm currently a developer at a small software development firm, and we are starting to adopt Agile (specifically, Scrum) philosophies into our culture and project management style. We have only a few developers, so it's important that billable work and efficiency are optimized.
From personal experience, our developers always have more work than our designers, who, empirically, have 60% less work on average per project. If a single user story is estimated based on a unified effort (story point contribution) I see a few issues arising:
- The designer will always have smaller contributions, thus will estimate lower.
- The developers and testers will have substantially higher estimations
As far as I can tell, this results in a sprint commencing with a significant imbalance of work, tilting to the developers. This will not be apparent due to a unified estimate.
Instead, is it better to estimate on a per-person level, and stop when the developers have a full sprint. Sure, the designers will still finish early, but at least it's known by their own personalized velocity.
Strict Scrum may say that the designer should work on adding extra value in alternative ways (refinement, code debt in the CSS, etc.) but given we are small, we need to make sure each hour we put in adds significant, just in time value out.
EDIT: This might result in a phenomena of continuously slicing stories into equivalent areas - up to a point - but I don't think that's the point.