I think I’ve mastered the Art of the Beta Test. 
I don’t like Open Betas. For one thing, you get a hundred people catching the same first couple of errors and then missing the rest.
Me, I prefer to run Closed Beta Tests in waves. I give the link to about 10 people who can reply quickly. After I fix their issues, I slowly invite more people as my inbox becomes empty.
This way, I can keep getting fresh eyes instead of having everyone spot the same couple of errors. Those that come in at the end of the beta will have less errors to find, but that’s okay.
I also reply to every single email/feedback that is sent to me. Yes, that’s 80-something testers and sometimes 10 emails a piece, but I think it’s worthwhile.
The only downside to this method is that you might get a big awesome idea/feedback later in the process, which means more devastating changes to make. But for me, I don’t like anyone to see my work until I’m ready to share it. I don’t share my WIPs. Personal anxiety, I guess.