At this point I just make a quick guess and try not to spend any more time thinking about estimation. In my experience, all time spent estimating is time wasted

At this point I just make a quick guess and try not to spend any more time thinking about estimation. In my experience, all time spent estimating is time wasted. If there is some hard date that needs to be met, I have the luxury of ditching features that we don't end up having time for. If you're in a situation without that luxury, you have to everything in your power to keep expectations in line with reality.