Bait swims for big fish and the margin. Fish the big fish swim for ten minutes and if there is no sign, I would revert to the margin but continue to feed thetwo swims (at least). Keep an eye on what's happening on either side of you and every 15 minutes or so, go out and fish the big fish swim. If you start getting the bigger fish regularly, stay with them, but if that swim dries up, revert back to the margin. If you see those on either side catching big fish, it might be just as well to fish the big fish swim for longer, but keep the margin swim going.
I won a 100 plus pegger on the Basingstoke once where I could see almost every inch of the bottom right the way across, but I could not see the fish I was catching. On that occassion, those around me filled it in with groundbait and everything, but I doubt if I used a half pint of casters all day. Sometimes it pays to be a little frugal with free feed, when everyone else is chucking in tons.