That's why we were using complexity estimates in points (say 1 to 5) instead of actual time estimates in my last startup. Once you have some worklog, it's easy to calculate how many points the team can get done in a week (or whatever your estimation cycle is). This little abstraction made estimates much more reliable.

I guess some "agile" methodologies propose a similiar approach, but we didn't really follow any specific one, just figured out what works best as we moved along and kept the process as lean as possible.