The biggest thing with boards is there is a time to use them, and a time not to. If you are trolling a shoreline that isn't straight, back bay or some area what you will need to make constant boat corrections to stay in your desired depth, they are not the best way to go.
I really like to use them at Sak when trolling open water on the main lake(not in a bay), or if I want to run a crank close to shore in shallow water without having the boat scare fish or be at risk for hitting a submerged rock. I find with boards, they are great for suspended fish, trolling cranks or spinners, but also give me the option to troll different depths. My four rod set up will be something like this. 8'6" rods off the side with boards, and some combo of cranks/spinners running at different depths, and two rods off the back either a straight line or lead core. Again running different depth lure combos off the back. I find this set up allows me to run different parts of the water column and different lures until I can get it dialed in to what the fish want that day.
There are days at Sak in those hot dead calm days, the boards work wonders trolling because of how clear that water can be. Also allows me to cover a great spread as you mentioned.
Forgot to mention, they really help keeping lines spread. I hate getting tangled up!!
