I only use straight when doing 'large' sheet film (8x10 or 11x14) because when I started, I was doing them tray, 1 at a time, and the longer times were killing me.
Now I use a jobo, but having five 8x10 sheets in one tube make me worry about the dev dying on me if I don't use stock. When I used trays, I re-used it in the tray til I had finished at least 6 sheets of 11x14. Can't remember exactly how much chem I used though?
I never re-use it when I'm doing roll film, as it's diluted, and I feel like it would exhaust sooner, though I can't really back that up.
I will say I love this stuff more than almost anything.