That’s a bit of a cop out though. First you are throwing a big chunk of the part of a system that can take high variance time (the analysis) out of your estimation accuracy. Second no rigorous studies have shown that breaking down tasks into smaller chunks for estimation purposes changes the accuracy rate of the broader actual ask.

Anecdotally what happens when you do the breaking down into smaller tasks thing you are either just putting off giving the broader estimate (in systems that only estimate the currently workable tasks) or you are likely missing small tasks from your broader goal that will impact your estimate later leading to standard estimate overruns.