Personally, I have found it useful to make private estimates, and then be honest with myself about why I did not meet them. It has made me a better developer, and incidentally also better at estimating.
What, if anything, I say about these estimates to anyone else depends on the culture of the environment, but the experience of estimating has made me better at explaining why it is going to take longer than you think, when that case needs to be made.
What, if anything, I say about these estimates to anyone else depends on the culture of the environment, but the experience of estimating has made me better at explaining why it is going to take longer than you think, when that case needs to be made.