OK, yes there's often correlation but that's it. A longer pipeline doesn't affect max circuit frequency.
The other sibling comment regarding distance isn't true. regardless of how insane your feedbacks are. Physical placement tools have always handled this in my experience (as a chip designer for 10+ years).
There is no point of lengthening the pipeline if you don't get higher frequency from it. It would just add complexity and and a higher branch mispredict penalty.
