For me, you never really mark the fish in the top 10 to 15 ft of the water column. But 9 out of 10 times, the biggest fish of the day will come from that bait that is running in that top 15 foot. Also way too many times for me, I'm marking plenty of fish suspended, but the bait running just off bottom is the one taking most of the fish. 30 ft is fairly easy to cover, say, 20, 45, 70 and 90 out would do that ( 45 to 70 is only a 4ft difference in depth). Getting bit at 45, bring one rod up shallower to like 35 and see what happens. That's why I cover the water column. For me that's how I dial em in. As the sun comes up, usually so do the active fish. 60 f.o.w is more challenging but we usually have at least one more on board so 6 lines out. But that's my experience.