The guys on salt water who use a scale, set the drag much lighter on the scale than you would ever dream of. For 16 pound test tippet, they will set the drag at about 4 pounds of pull.

By all means, use a scale if you want. It's a great way to get a feel for what you are doing. If you hook a scale to a doorknob and pull, you will find it entertaining to find out how little pull you are actually putting on a fish, and therefore, how much you can really reef on a fish when you want to.

I want my gear rod drags set at about 1/3 of the line test. So, for 20 lb test, I want about 7 lbs of pull to pull the drag freely. That sounds light, but it's actually pretty stiff, and will definitely cause the hook to set it self if the fish runs against it. This is for plugging rods, with the rods set fairly low in the holder. Gives enough tension to set the hook, not enough to break rod or gear. You can always thumb the spool to give more resistance if needed.