Serious question, though consciously naïve: how could boxers from other eras fight SO MUCH?

I have seen this in amateur boxing, and recently so. One kid in my gym was sent from one tournament to another, so he was basically fighting 3 weekends in a row. During the weekday training he did not do any sort of sparring at all, just worked on drills and mitts.

Its actually not difficult to fight every weekend, I see it in our Friday sparring sessions. There are guys who barely train at all, but show up every Friday to do some sparring, which often ends with some action packed rounds to finish it off. Usually we do 8 or 10 rounds, but these guys go for 12.
So as long as you are not injured, its not that difficult. I will never understand why guys dont sprinkle in more easy fights into their schedules. Keeps them sharp and earns a quick buck.

 

Well, you mentioned Buck Smith. I used to watch Smith fight all the time. And Smith was very vocal in that he never sparred. Competing in boxing matches was his sparring.

Buck Smith would fight multiple times a week. Most of the fights didn't last long. It wasn't too taxing for him. He even fought twice in one day a couple times.

Most fighters today, for major bouts, shoot for 100 rounds of sparring. That's ten 10-rounders in two or three months. You can say sparring isn't the same as fighting but take Fury, for example. Five or six years ago, he'd spar 100 rounds with Joseph Parker preparing for a fight. That's 100 rounds with a pretty good fighter.

Fighting ten 10-rounders with Parker is certainly more taxing than Buck Smith fighting 10 or 20 no-hopers who rarely won a fight on the Midwestern circuit, and watching them fall down in a round or two.

Also, there were day-of-the-fight weigh-ins when Pep and Robinson and those guys fought. You weighed in when you showed up at the arena the late afternoon of your fight (that night). So everyone was "walking around" in the weight classes they fought in. If you were fighting multiple times a week, you weren't trying to cut weight all the time. You just remained in shape and showed up at the arena.

That's why middleweight fights would have guys weighing 155 fighting someone who weighed 156.

You NEVER see that anymore.

Now, everyone spends months drying out. They barely make the 160 limit, and they quickly rehydrate 20 plus pounds.

If they have same-day weigh-ins, and your fit weight is between 155 and 160, you can fight on Tuesday weighing 155, eat a couple heavy meals, and still fight on Friday weighing below 160. And then run some miles, and fight again the next week between 155 and 160.

If you're drying out 20 or 30 pounds to make weight in a division you couldn't actually compete in without passing out, you can't fight every week.

Moving the weigh-ins 30 or 40 hours before a fight screwed up a lot of things. One of the things it screwed up was the actual number of fights boxers had.

 

Genetics plays a part even tho some people don't want to hear it

 

Two reasons.

The sport wasn't built around being undefeated. Boxings like college football now.

Big fights were less lucrative because they were limited to a local audience. Historic boxing live crowds are a small audience by PPV or television standards. Before TV cashing out in a few big fights at the end of a career didn't really make sense. Fighters wanted more paydays not less.