Comment by ben_w

My experience is that when I ask for a clear and well defined problem, of the scale of "add motion blur (linear, spin, and zoom) to the filters menu; include standard dialog box (see existing design) for user input on all options", this works something like 90% of the time, is obvious garbage 5% of the time (in my experience, when it claimed to be writing "unit tests" it was actually performing regexes on the source code), and is subtly wrong the other 5% of the time.

If you use the planning mode, and your first move in the project is "write plan to reimplement photoshop" then you blindly say "continue" until the plan is done, then you get 0.9^{number of features} success, which of course on the scale of photoshop is going to be a failure. But this is still in one sense a 10x speedup in that 9 times out of 10 you're only doing code review, not having to re-write it. But code review is a real thing, so it's 10x on writing code not 10x on delivery.