[mjohn]

No, because it's often very hard to estimate until you're actually working on something. It's common to get a consensus estimate that something is "easy" only for some poor developer to be left with something that is "hard" and takes much longer than estimated.

Also, something might genuinely be easy for someone who has worked on that part of the codebase before. But it could take someone new a long time to get up to speed, again making that developer look bad (this is not to advocate that only devs familiar with the code should work on it - you want to spread the knowledge around).