I never want to think or try to do anything where my arms are acting independently of my torso. I set my lead arm on my pec, and I turn back as far as I can without swaying or losing the brace of the trail leg.
Classic long hitter instruction talks about width and such, but you don't have to have a big backswing in order to hit the ball a ton ( Allen Doyle ). In fact most ams won't hit the ball farther or better with a bigger backswing - more time for things to go wrong, hard to sequence everything with a bigger arc.
If you have a swing that has proper tempo, is sequenced well, and hits the absolutes, then a bigger arc may help you hit it farther, but the main distance factors are the same things that make for a good swing period. If you make a good turn back that builds torque, execute the Vital/Master move, keep the dog's hind leg, maintain trail wrist bend through impact - you will hit the ball far. Maybe not far enough to compete in the long drive, but far enough to be hitting lotsa "flip wedges" for approaches on most public courses!
Never quit til you have a swing you'll never forget!