Ironically at the time it was probably considered not enough considering how often the fighters of the previous generation fought, Harry Greb comes to mind at 45 fights in a year I believe lol
To be great, one must be willing to do great things. What Ali accomplished, and many other fighters until the 2000's proved. Of course they did it for the money, but they also did it for their competitive spirit. They dared to be great. They understood to be great, one must place themselves in a situation, or fight were they could conceivably lose. To be the best, one must fight the best available. Or, fight often enough were the law of averages and a off night could see the fighter lose though he is the superior fighter. Fighters today for the most part are in it for the riches. And the easiest way to get their is the Avenue they take. That's why in my opnion they will NEVER have the impact of Ali vs Frazier , Pryor vs Arguello, Leonard vs Hearns, Duran, or Hagler just to name a few. Ali didn't need to fight Frazier again, probably could've ducked Shavers, Lyle, Norton, but if he did, he wouldn't be the greatest heavyweight to have ever lived.
Sure, I'm making some assumptions about the punching power of fighters I've never seen but only read about. How are you going to even discuss fighters who have never been filmed without making reasoned assumptions? Of all the fighters Greb fought during the 45-fight run you mentioned the hardest puncher was probably Bill Brennan whose best weight was about 195-198 pounds. We have good footage of Brennan on film against Dempsey, and I see no evidence that he punched anywhere near as hard as Frazier or Ali.