One approach I've used is to go out 1.5-2 hours before a tide change, drop traps, head to a nearby salmon spot to fish the hour or so either side of the slack. Back to traps, empty the catch and reset for overnight. You get two pulls in the one day, plus some fishing, all for about 4 hour time investment. I'll shallow up a bit for the overnight soak since prawns usually migrate upward at night.