Were Masks a Waste of Time?

I have been waiting for a particular type of study on the current pandemic and this isn't it, so I'm going to comment a bit about the book I want to see as well as what we have here.

As the reviewer and the book author note, analyses of non-pharmaceutical interventions during the various pandemics of the 20th century have all supported that mask-wearing mandates had no effect on spread of the diseases. Hence, as of early 2020, it was the common position of Western health agencies to discourage public mask-wearing.

However, in spring of 2020, governments all did a flip and instituted mask mandates. What I want to see is a detailed study of what happened. Was there new scientific evidence or was it all political theater? Unfortunately, this book doesn't deal with that. From the review:

Miller confines himself to the data, and if there’s a limitation to his book, it’s that he does not offer any compelling explanation of why the expert class threw itself a policy it once regarded as worse than useless.

Now as to the book actually written. It is primarily an analysis of data collected during the current pandemic to evaluate the effectiveness of mask mandates. His conclusions appear plausible because they agree with studies of previous pandemics, but my experience with analyses of complex events so close to the fact is that they are often subject to revision after longer analysis.