Yeah, I've learned that it's only worth deploying Fable for the most challenging problems. For a while, my Fable workflow was looking like ths:

Me: Hey Fable, I've got this massive, theoretically challenging, totally novel, ill-defined cutting-edge problem that I'd like you to solve.

Fable: < Doesn't merely solve the problem -- utterly obliterates it. Nukes it from orbit. Does a robust one-shot that takes several hours to complete. >

Me: Holy smokes, that was amazing!!!! But the formatting could use some simple refinements. Could you change the margins and maybe add a drop-cap at the start of each section in the user docs?

Fable: < Commences another multi-hour nuclear exchange with the code >

Me: WT?!?!

(The moral of this story is that bringing a nuke to a knife-fight is only occasionally the best strategy. And in more practical terms: Fable is amazing -- but only for certain classes of problems, and even if it were free there's a lot I probably wouldn't use it for.