When I maintain a spot over the medium or long term (e.g. for a session or to do regular fast fishing on that spot), I always bait one spot only. In this case, I only fish with two rods, never more.
Bootstrapping concentration and food competition
I have decided to bait only one spot for two main reasons:
1) Firstly, I concentrate the quantity of bait at my disposal on a single spot and don't fragment it (which is also a financial argument...). To proceed in this way, rigorous surveying and scouting are essential. Chance has no place in this approach.
2) And by baiting in this way, I don't scatter the fish but concentrate them and create feeding competition.
Only 2 rods on this spot
Not putting 3 or 4 rods on and around the spot is above all a question of discretion. With two rods, I only have two "banners" in the water and, in my opinion, disturb and stress the fish in the area much less. Carp are, in my experience, very sensitive to wires in the water. Too many wires stress them quickly and permanently.
Two rods, on the other hand, are sufficient to fish the baited spot properly. Of course, both rods are placed on the bait. The aim of gathering fish on a single spot is to create a competition for food that makes the fish less wary. Two rods will be more than enough for a succession of starts.
They allow, if necessary, two different presentations at the start to determine the optimal presentation on the spot (balanced, dense, floating boilies...). They also allow you to let the second rod fish without restarting the first. But I've lost count of the number of near-simultaneous starts I've made using this method. Yet another reason to limit yourself to two rods, as the situation is sometimes complicated to manage when starts are simultaneous.
The exception that proves the rule
I have only two exceptions to this: removing one rod and fishing with only one rod when there are too many starts or when I notice that the fish in the water are very wary and two lines scare them off.
Fishing with only two rods is often initially frightening for anglers used to fishing with four rods. But many anglers who have tried this approach have never looked back. And last but not least, I know a number of anglers who have switched to two rods, and have taken advantage of this to be able to afford top-of-the-range equipment, since they now have half as many rods, reels and sensors in their fishing.
