When I started playing seriously in the early '70s it was common to have one shaft for Straight pool and another for 9 ball. One was a bit smaller diameter than the other but for the life of me, I can't remember which. It seems like the prevailing thought was that you would use the smaller for 9 ball, using more english than playing Straight pool.
Since the late '70s, I've always ordered my shafts the same size and alternate between the two so both will remain playable. I've only ordered a cue with one shaft once, I think, and ordered a second within a week.
I've never heard of anyone who used a specific shaft for One Pocket but I don't see anything wrong with the idea. I currently prefer stiff shafts myself and use the same shafts for all games.