During my freelancer-time one of the things my clients valued most was (A) my speed and (B) how precisely I could give them a timeline ahead of time and keep it (aside from the occasional client-induced change).

I am convinced you recognize real pros from their ability to tell you how long things will take (provided they know the details of the project of course). Beginners are struggling to even accomplish the task, so they can't give you any timeline.

I am aware that there are projects that are even hard to predict for the expert, especially if there are many moving parts and unknowns. But then the answer should be a pessimistic guess.