Harry Greb fought 44 times in 1919. Most were 10 rounds or more. He fought well known boxers such as Battling Levinsky, Bill Brennan, Willie Mehan (who defeated Jack Dempsey), Mike Gibbons, The Zulu Kid, Mike McTigue; several of them more than once. A few KO's and all the rest were newspaper decisions....he didn't lose one fight all year! Could any modern boxer fight 44 times in one year? 10 round bouts. Any level of boxer; let's say 40 of them were walk overs and 4 were genuinely good, ranked boxers. Well?
Oh and he had broken his arm in late 1919 and had ptomaine poisoning in January. And had boils much of the year.
44 bouts in one year? Sure its possible. Look at some of the journeymen that have 100+ fights. Most are 4-6 rounders. Now 44 10 round fights in one year is a pretty big ask. I haven't checked but I would think in the 90s maybe someone like Jakubowski or Buck Smith may have done it but I doubt they fought 10 rounders mostly. Id nominate Canelo, he could probably murder 40 journeymen and fight one higher profile fight every 3 months if he wanted. This is all contingent if he doesn't get injured or get a nasty cut. Fury could maybe do it as well. I think a more active schedule would be beneficial for Fury to stay in shape and stay sharp. He also doesnt have to worry about making weight. 44 fights is pretty overkill though. Also the training camps would have to be changed since these guys are fighting almost every week.
If JC Chavez is considered modern, he could have done it. Prime Roy, prime B-Hop and prime Toney, prime Floyd if the hands hold up. Spence Jr, Crawford, Usyk, Loma - basically guys who stay in good shape and can stay away from inside wars as and when required. Realistically, boxing politricks, sports science and the money involved means that Greb's era of fighting so often isn't going to be repeated, neither is it necessary or potentially safe. The increased risk of irreparable damage trumps the opportunity for achieving greatness. A happy medium for me would be fighting consistently and making the biggest fights with the best fighters available happen whilst respecting your health and not putting your body on the line almost once a week.
They'd pretty much stop sparring and use the fights for that instead. Most of the top guys' sparring partners are probably at least on the level of the fillers in Greb's resume, so why not. Pretty much just fairly light training in between fights and use the fights to keep sharp and in shape.
I mean, if we look at some of the greats' sparring partners: Just off the top of my head - Louis had Walcott (although the rumours are that he got kicked out of camp for being too good), SRR had Cocoa Kid and Lytell, Charles had Liston, Ali had Ellis and Holmes, Frazier had Norton and Young, Tyson had Page and McCall, Holy had Bowe and Tua, Wlad had AJ and Usyk, Pac had Mikey Garcia, Bradley had Crawford, Floyd had Judah and Spence. These were all pre or past prime and most weren't sparring partners for that long, but it still gives an indication of the kind of quality that the very top fighters spar hundreds of rounds with for a single fight sometimes.
Toney and Hearns likely had sparring clashes better than some ATGs best fights. Difference between a spar and an actual title fight though are significant though, especially mentally. Throw in 6 - 10 title fights mixed with tune up/stay in shape/sharpening skillset fights in between, then a fair few modern greats start picking up losses/having more off nights.
Smith and Jakubowski both had over a hundred fights, 44 is a bit much in a year but over 30 I wouldn't be surprised (like i said probably 4-6 rounders). Kristian Laight had 300 fights so I'm sure he put up a lot in a given year. Do I know Canelo or Fury could beat 40 low level journeymen and 4 higher level fighters in a year, obviously not. But in this hypothetical world where this scenario is feasible sure maybe they could.
No. Not even enough fight clubs around today. TV changed the landscape in the early 50s. Many fighters went away as the small clubs died.
It would take someone with deep pockets and connections. The OP didn't really specify this in this hypothetical. In the real world 44 10 rounders in a year with 4 contenders and 40 journeymen yea probably not ever going to happen like ETM says. Now COULD they physically do it? Sure a few probably could.
You're assuming Greg did not sparring between fights. He did no exhibitions that year, but he absolutely sparred before his most important fights like the Brennan fights.