[js8]

> I wonder whether any formal way of estimation actually works

I agree that it is a legitimate concern, I certainly do not advocate a position that software cannot be estimated or planned at all. I think it can be, but only up to certain time granularity, where the attempt to gain understanding for a sensible estimate (and describing what needs to be done) becomes essentially comparable to writing the code in the first place.

I actually have an underdeveloped idea how we could have a completely formal approach to tackle uncertainty in SW development, but it is purely theoretical so far (using a combination of functional programming and information theory).