I tend to use 1024 to 4096 for crossing long stretches of open ocean where I don't expect to run into anything.
128x for patrolling in aircraft rich environments, it tends to ensure a proper amount of aircraft encounters, but gives you enough time to respond
512x when loitering at 20m for hydrophone-based hunting in shipping lanes
in other areas I use 256x
short bursts of up to 64x when approaching targets (gets it over with quicker) and 1x for dodging DDs
