I don't block any but, as an Admin, I tend to check on all communities (theoretically) in case there's shenanigans. As I am on a smaller instance Local is manageable and then I use Subscribed. All is too much of a firehose of content to use much. So I am more opt-in than opt-out.
My preferred way to browse here is using All and blocking communities I don’t want to see. That way I get exposed to new things I wouldn’t seek out on my own (for example: British archaeology)