I never get fish on the reel. They are the ones responsible for that.
The way I see it, my job is to get the line back onto the reel - in other words, retrieve all the backing to get the fight in closer where I have the advantage.
Perhaps in a twisty river with pucker-brush everywhere with a large fish that you have to chase down, it may be necessary to have all line in order to even move.Then I suppose, just very carefully.
As for setting drags, just don't go too tight.
To give you an example of actual poundage, I set my drag for tarpon using the following method. I strip line off the reel to where the running line is nice and uniform, or until I hit the backing. I tie it to a 5 lb. dumbell and hold it (reel and weight - no rod attached)
at head height. I then adust the drag to where the dumbell will fall to the floor in 4 seconds. Then I back off three clicks on my drag knob.
My guess it that I have about 3 1/2 lbs of drag. And I am using straight 60lb leader. When fighting the fish after he quits his wild panicked jumping and running, I tighten it back up three clicks until he is next to the boat, where I back it back off again and palm when necessary.
The reason is not so much being afraid of breaking my line, but of pulling, bending or breaking the hook with sudden shocks when there is not much line out.
That would also be my concern when fishing 4x or stronger leaders. The typical figures I see with salt water fishing is 15-20 percent of class tippet strength. So 20 lb tippet, between 3 and 4 lbs. I would say, you would be in ounces if you were to do it that way.
The other suggestions are good ones. I don't think drag is a big issue with freshwater fish so long as it isn't too tight.