. A guy like GGG for example is elite level boxer and that factors against physical break down.
Why against, GGG had damn long mileage in ams under belt, most likely even more than Usyk if count stuff like smokers, the same about Bet etc boxers.
It is not good to have >200 am fights ( including very hard smokers ) under belt before you turn into a pro.
Ideal thing is if with you happens stuff like with DLH etc fighters.
Young, with low mileage and still enough exp to get a pro.
Not stuff like I had saw: both ends: one: approx 15 am fights, another > 250 am fights under belt.
Some fighters are done at 32, especially at the lower weight classes others can go at 90% quality into their 40's.
It depends from you, some gets more earlier, so no no offenese here.
Marciano, Ward, DLH etc, lurk in first retirement age. A lot of fighters and there nothing wrong.
In disciplines where timing or other measurable criteria are used, some from athletes are told that they are old when they yet are not 30 y.o.
Results, math and concurrent results etc things.
Sport is very harsh, even non combat sport is damn sharp and harsh thing.
In pro boxing it is there also thing that you need to get so called resume, and before you are too old.
It is not like pro soccer or basketball, where the better you are, the more offers you will have in row.
In the same pro boxing, unless you have big money behind you, then, the better you are, the more difficult to get next fights.
Some fighters even are sneaky, they with intent looks not good and craps point wins in order just to at least to get next fight and pretends to be worse than they are IRL.