I give estimates in hours. They're really by days for large projects and half days for smaller projects, but I express them in hours. I then provide a breakdown

I give estimates in hours. They're really by days for large projects and half days for smaller projects, but I express them in hours. I then provide a breakdown of the hours the team has been able to spend to date, as well as the hours that each forced interruption took. That way, when my manager asks why he perceives us as being behind on the project, I can tell him exactly how long his pointless meetings and changing priorities have delayed the team. It's also a good CYA technique for when he tries to blame the team when his manager asks why the project is delayed.