I have never trolled and don't really know the first thing about it, but I have seen them doing it in years past. Ive seen all the rod holders mounted on the sides and back of boats, and soooooo,
Ive always wondered how in the world you keep from getting your lines tangled?? Does it happen on a regular basis?
Or is that the fun part
Generally the answer is, "No." I troll jigs for crappie primarily - usually I have six lines out. Sometimes I use planer boards but other times they will all simply be on long lines. I generally have a 10-12 foot rod in the front holder (set at a 90-degree angle), and 6-8 foot rod in the midship rod holder (set at a 45-degree angle) , and then 4-5 foot rods in rear holders straight out the back of the boat. That configuration provides good line separation and allows me to basically cover about a 25-foot swath, and the jigs always run straight and true.
On occasions a good-sized crappie might run sideways and cross another line, or even two lines. However it is generally not a big deal. Often you can simply maneuver the rod over the crossed lines and just reel the fish in, no problem. Even if a line remains tangled, it's usually quite simple to untangle or straighten out, with very rare exceptions..
The only time I've really had a problem tangling lines while trolling is using crankbaits. If your crankbaits are not tuned properly and don't run straight and true, I have created some serious messes. But that was operator-error, not a problem with the methodology.