It’s easy for this honest mentality to turn into malicious compliance. If you’re actively fulfilling that prophecy, this won’t just impact a manager or a PM, it will absolutely impact you as well. I’ve seen it happen many times, obviously this goes beyond just being wrong or missing deadlines but eventually it will come back around to bite you.

At the end of the day, these estimates are helpful but maybe not in ways that are intuitive from a developer’s perspective. They’re useful in weighing priorities, judging the uncertainty, and identifying where to fill the gaps in understanding, time-boxing research and scope (e.g. do we really need to spend 6 weeks reading release notes?), and help communicate to outside stakeholders. We see the successes of this all the time with big game releases, product launches, movie releases, etc. It’s a high level measurement of progression and devs need to be a part of that planning process. It gets easier for senior engineers to do this efficiently with experience. It’s not necessarily an exercise that a more junior engineer will a) get right consistently or b) think is valuable at all.