> After looking through the code to start implementing one feature (4 weeks into the 3 months) the team realizes there is need to change another team's API. On

> After looking through the code to start implementing one feature (4 weeks into the 3 months) the team realizes there is need to change another team's API. On the estimation side of things, I've worked with teams that do estimates in concrete hours, days, weeks, etc, and teams that work in abstract feature points, bushels, etc. The number one factor for whether the estimates are successful is the time spent before providing the estimate to figure out what the actual scope of the task is. If you've planned and estimated a task and didn't discover the cross-team dependency during that planning, you've failed at planning. It happens. It sucks. It should be very rare. I've worked with teams where "sprint planning" every two weeks/whatever cadence is basically an entire engineering team getting pulled into a room for a morning, the manager/scrum-master/whatever pulls up their backlog and starts picking tasks off the top. The team is expected to provide estimate efforts on the fly in the meeting, and then expected to spend the next two weeks perfectly executing on the work they've committed to. How in the hell is a process like that going to allow people to really think through the issues that are going to arise (like needing an API change on another team, or even verifying that a 3rd-party API is compatible with what the task is trying to achieve)? These teams constantly run into the issue you've described and it absolutely sucks for everyone (the business, the managers, the developers), but the process just keeps being adhered to. Maybe in the post-mortem someone will say "we need to do a bit more analysis before doing estimates", and the outcome is that during the next sprint planning session the SM will say "HAVE YOU REALLY REALLY REALLY THOUGHT THIS THROUGH?" but... they're still doing analysis on 12 new tasks blind...