I agree. Saying, "Break it down until it's in half-day size tasks" is fine. Some of the things that might interfere: 1. Are you sure you can do that in half

I agree. Saying, "Break it down until it's in half-day size tasks" is fine. Some of the things that might interfere: 1. Are you sure you can do that in half a day? 2. You forgot about this one part of the task that you thought would take half a day. 3. There was a bug in the plugin that you were going to use to do this task in half a day, and you spent three days fixing it. 4. This task will actually take longer, but management won't buy that. Looks like it should be half a day on paper, so that's what we'll say. 5. I've never even done this one thing before, but it sounds like it should just take a couple of hours. I understand the concept - trying to say something will take a week is even more error prone. But I think most of us are still pretty bad at estimating a budget for tasks even at such a small scale.