I don’t understand the question. It is not relevant how people learned daf yomi in 1923. Just like they had different abilities and skills 97 years ago there were also a lot less people learning it then. The primary beauty of daf yomi is the structure. It obligates a person to stick to a schedule and keeps him on track. A secondary advantage is the idea of connecting with Jews all over the world. The level of depth a person applies to it will depend on a person’s abilities, time constraints, tools available etc. If a person is learning in kollel and can put in 4-8 hours a day into doing the daf -great. If he is a beginner learning it for an hour a day that also has a huge benefit. Every person needs to choose a learning program that best suits him.
I think if you compare the learning of those who learn the daf and the detractors you will see a big difference. Most of the detractors do not come any where near the daf adherents. They use it as an excuse. Would it be best if everyone would break their teeth trying to figure out every word of Gem. Rashi & Tos? Yes but the reality is that the only ones that can do that are big talmidei chachamim or people learning in yeshiva all day. Unfortunately, there are are many bachurim and kollel yungerlite who do not reach the same level of yegia and yedios of many balei batim daf yomi learners.
I never met Ra, Meir Shapiro but my guess is that if you would ask him this question he would say “just learn as much as you can!”