I think it can be a crutch.PerroneFord:I have to be honest, doing deco today with the spool, and making 10ft stops was the cleanest deco I've ever done. I've been trying with marginal success to just do it looking at my depth guage, and I'm just not good enough yet. The spool made things a LOT easier.
Sure, it's easier to hold your depth by being just a little negative and slightly hanging on the spool. The way I try to avoid that is by just hanging beside the untouched dangling spool or just doing the OK with my thumb and index finger around the line to prevent it from drifting away. Otherwise it's easy to get used to having something to hang on to.
MHO. YMMV.