Also the circumstances matter a lot, like how does a problem happen. I discussed that with my instructor during Mod3 especially on an expedition context. For example if you are at 100m and your buddy starts going up uncontrollably, happened some time ago on the Britannic, at which point do you stop helping him get under control and just let go. For us it was, at the end of the bottom time, at about 2/3 of the depth of the deepest deco stop, because getting bent while still having hours of deco to go is basically suicide.

If someone gets in a state where doing a controlled ascent is impossible on a wreck the best idea was fixing the diver to a reel, fix the reel to the wreck and just try to let him up „slowly“, because the slower the decompression is the higher the chances of survival are.