I just helped a Honduras charter skipper with his new (to him) boat. It was a glass boat with 300 hp Suzuki ob. He could not catch fish at all with it, even when fishing beside his buddies boats. He had stainless trim tabs and a bronze through hull that were not bonded and had no zincs. He ran the wires and connected everything to his ob. Next time out he hooked into a blue marlin within 10 minutes and had 3 and 4 tuna on at a time during his day on the water. Such a seemingly small thing can make all the difference.
He did have a stainless cavitation plate, but it still was not enough to make his boat fishy. By including the trim tabs and through hull fitting to his bonding system, he increased his ratio to maybe 10 to 1(1 being zinc).
I just did my annual spring trout outing for 5 days. I loaded up my 14 ft Lund with all of the anodes I owned. This brought my ratio up from 350 to 1, up to about 100 to 1 (exposed surface area). This was our most successful fishing trip ever on that lake. Fish were not only being caught close to the boat, they were a bigger average. One trout even broke water within 2 ft of my stern. You do the math.