My opinion is you're not hurting anything by reeling, but you aren't accomplishing anything either. I'm not an expert, but I don't lose many big fish. I frequently experiment with my rod, reel and line. I'll tie my line off to something in my yard and get a feel for how much my line can take. I also do this with knots. When fishing I keep my drag fairly loose, I'd guess 3 or 4 pound but I've never checked with a scale. I thumb my reel for a good hookset then let the fish do what it wants for a while. If it's headed toward cover, or somewhere I don't want it to go I'll thumb my reel to put additional pressure on it. This is where experimenting in my yard helps me know how much pressure I can put on a fish. Once I've got a bigger fish "turned around" I bring it to the boat my pumping the rod. Reel while lowering the rod tip, thumb the reel, pick up the rod to pull the fish in, then repeat.
It may not be the right way but it works for me. I used to back reel like @Captain Phil but just use a light drag setting with my thumb lately. When I was 12 I lose a HUGE bass by leaning on it too hard. That's when I started experimenting by hooking my line to stuff in my yard. A couple months later I caught a 20 pound striper.