How do people peer-review many papers?

I am an Assistant Professor of Chemistry. I try to be an active peer-reviewer but on average it takes a few hours to review a manuscript (reading, some searches in the literature, checking some relevant reference, and finally writing the report).

I review 2-3 papers per month and I need to spend some time outside my working hours. In various blogs, articles, websites like publons.com, I see it is not uncommon to review 10-20 papers per month.

Then, I came to the conclusion that I am doing something wrong. Because by my calculations, it is impossible to peer-review many papers along with various tasks of an academic.