Re: The ETags rule and how it’s applicable to smaller sites.
I believe the rule applies to smaller sites. Although they are served from one server, they often move.
A smaller site is usually hosted on a low cost shared server. I can tell from bad experience that often you’re wrong about your choice of hosting provider. Either tricked by a “review” from the provider’s affiliate, or by the promise for unlimited something (bandwidth, space). So after a while, maybe not even a full year, you move your site to a different provider, meaning on a different server, meaning different ETags. Also even if you stick with the same provider, sometimes they decide to move you to a new server because of their internal restructuring or any other reason.
Given how extremely simple it is to configure ETags, why skipping this rule?