This is so neat, as Phil mentioned in the How to run a software bookclub post, out of a group of 500, only 1-2%, 5-10 people may contribute with comments. But he lets the group grow in size because it is minimal overhead and many "lurkers" say they really appreciate reading the comments and get a lot out of it.
I am left wondering is there any way to see past comments on book discussions? I would love to read the discussions as I go through a book already done by the club on my own.
I keep thinking about doing future ones semi-public (need to sign up to be allowed to post) but I already spend more time on the book club than I particularly want to so I mostly just keep doing the same thing which works fine enough. It's also not unlikely we'd repeat a book in a few years (for example we'll read DDIAv2 probably next year). So for now, join the mailing list and new readings as they happen.