In over ten years of keeping snakes, I have only soaked a snake one time... It was a garter being treated for parasites that damaged connective tissues, and the shed was retained and literally only coming off one scale at a time.
All other times I've had shed issues, letting the snake crawl through wet paper towels and/or shed boxes have done the trick. I might up humidity a bit right before a shed, but I've never done a preemptive soak.

I just don't see any evidence that a pre-emptive soak is necessary for a good shed. If it were, I imagine BPs would be SOL in their native habitat. I can see it as a last resort for a retained shed that is hanging on despite all other options, but not as a preemptive sort of thing.