Three times until your estimates mean something on what you are working on.
The First Time – You’re new to whatever it is you’re creating. You are learning as you create, you are going down rabbit holes and filtering out new ideas and throwing away initial designs.
The Second Time – You know enough to be dangerous, but you are still learning. You have picked up some tricks, did a learning and validation of your ideas and now you are putting them into place for the first time.
The Third Time – You’ve been around the blocks a few times (literally) so you know what will and won’t work, so now you put it into practice and you execute. You know what to avoid and steer clear of and where to place your focus.
This is why there is a difference between juniors and seniors – the junior hasn’t done it yet, the senior has.
As a Leader, your job is to insulate their growth and failure each step of the way – giving them more padding on their estimates so they can learn and grow and become better at what they do.
Just like you did.