Given a really effective intervention for a contagious disease, the effectiveness on a community level will be much lower on an individual level. Think about PRC vs. USA: 4636 deaths in PRC, 618591 deaths in USA, even though it's a four times smaller country. There is no measure that even comes close to reducing your risk of death from covid by a factor of 600 on an individual level, but because they were able to get the R number down below 1, they stopped the epidemic.

Normally you would expect effective contagion control measures to have an exponentially larger effect at a societal level than it does at an individual level, even if you don't reach the critical threshold to stop the epidemic: if you can drop R from 2.0 to 1.9, that reduces your individual risk by 5%, but it also reduces the number of cases in the next generation by 5%, the number of cases in the generation after that by 10%, the number of cases in the generation after that by 14%, etc. After 20 generations of transmission you've reduced the number of cases by 64%, which reduces everyone's infection risk by 64%. Of course, with such a high exponential growth rate, that only means that people get infected 1.6 generations later at that point, but if you're comparing different communities at the same time, the difference is about 3:1.

So it seems like probably the effectiveness of the mask on an individual level was truly tiny.