Depending on the PM I've found giving a confidence level on an estimate to be helpful. For example on a task I've done a million times I might estimate that it

Depending on the PM I've found giving a confidence level on an estimate to be helpful. For example on a task I've done a million times I might estimate that it will take me 1 hour with 95% confidence. Other tasks I might estimate at 2 weeks with 50% confidence, same task 3 weeks at 85% confidence. As with all things communication, the audience matters and it's incumbent on the speaker to communicate in a way the audience can understand. So that might not work with everyone. Some of it I think is also personal confidence. If I tell someone it'll take me two weeks, I never budge unless new information becomes available. If you budge, you are welcoming being pressured/bullied into working overtime and/or delivering poor quality all the time to meet infinite demands. Also, we must accept that most customers are willing to accept lower quality/higher risk than we want to deliver. In this case what's important is to state the risks as plainly as possible and set boundaries on what you're willing to do before those risks come back at you.