I think by 1930, boxing as an industry was in a form that would be recognizable to us. Gone were the days when a man got a world title and not defend it for years, somethimes they went to pursue entertainment instead. In America it was second only to baseball in terms of popularity, so tons of supply of contenders for a title. The Great Depression made men fight for whatever purse was offered, even if the fight was risky or a disadvantage. Only some boxers were able to refuse poorly paid fights. Go back to 1928 as an example, take Featherweight/Jr Lightweights Benny Bass (101 -41-9) or Tony Canzoneri (141 - 24 - 10), they would fight 3 times a month, for years. What did they earn? A few bucks. They didn't care if they got a few losses. The money wasn't there, so keep taking fights.