Sometimes the cushions are more trouble than they're worth
so when we're racing we leave the cockpit cushions down below and just use the helmsman's cushion, not that I ever get to sit down, mind you.

Reason: they tend the fly around when sailing.
For cruising, we put the starboard one and the helmsman's cushions up, but leave the port cushion off. Reason: the port locker has a bit of important stuff we need access to, and the cushion makes it a pain. If the one cushions slides, it's easy to slip it back up - if it gets unwieldy, we stow it, most of the time it stays "tame."
Once we're in and settled, the port cushion comes out.
No hooks, no loops, no fasteners, no Velcro, no snaps.