I'm good at estimating what parts of a task will take a long time.

I estimate that the time estimate for any part of any task can be calculated in approximately the time it would take to complete that task.

> I'm good at estimating what parts of a task will take a long time.

I think it's trivial. I didn't say I can estimate how long the hard parts will take, just what the hard parts will be. If I don't understand something, I estimate that it will take a long time.