How do your teams handle scope creep or unexpected surprises that weren’t considered during estimation?

There are multiple ways that I have seen teams tackle this aside from buffering some additional time for unknowns that may creep up during implementation and research.

1. If this "extra work" is a must do along side other initial tasks. You will have to delay the overall product/feature launch by communicating the delay and why. This is a risky one and if happen often, will deprive the morale of the team and trusts from the top.

2. Similar to 1, convey the extra task needed and ask for additional resources to help with the project. This only works well if there are folks from sister team with cross team context that can help quickly.

3. Reduce scope of release and reevaluate what is the MVP that you will be delivering. This is what I tend to lean towards, by delivering incremental product/features if feasible.

One way I like to account for this is by under promising from the beginning. If two members think 2 weeks for a project, another thinks three then we agree to plan for 4 weeks. Worst case we deliver twice as fast as promised.

This early communication helps a lot because the PM and the designer may have thought they were proposing an MVP that could be done as just a quick change but then they hear a month and it gives them the chance to simplify more and think about what they want. As opposed to saying “yes” to 1-2 weeks when looking at the ideal plan and then having it take longer due to the unexpected.

Your estimates are only going to be as good as the work you put into preparing them. I'd encourage you to watch this TED video talk about how the most tallest structures were built by kindergarteners, and the people who did the worst were recent business school graduates. The major reason is that they spent focused on building the plan instead of following the iterative process by learning through prototyping and experimentation.