Gary. 1/3 of the # line is the rule. Some pull on scales to get it set at 1/3. Others like myself play the drag and listen to the line. Ping, Ping is too much drag
.
Trolling feathers I like to have a tight drag to keep the fish that get hooked near the boat, bringing the school to me.
Trolling diving lures aka Rapala, Yozuri, etc I like to have medium drag so the trebles don't get ripped out when the fish hits it.