I was just scrolling through some TV reviews... and the summaries of most reviews seemed to imply that the scores were given based on the pilot episode of the series.

For series that are still showing, it may be only important to review a series when it starts. But once a season ends, wouldn't it be more appropriate to evaluate the series again and give them a new score?

Generally, the pre-season reviews are based on (for most shows) the first 2-5 episodes, depending on the show. But often, reviewers only focus on the first episode so as to not give too much away.

But your point is well-taken: sometimes shows have lousy pilots and still end up being pretty good. 30 Rock was so-so through the third episode, but has really gotten funnier.

Rarely does it matter.......shows on the cable networks usually deliver more than one episode to critics, while most of the junk on network television usually only ends up being even weaker than the already dreadful pilot...occasionally, there's an oddball like 30 Rock that defies the odds and grows from "meh" to "brilliant", but there's probably been like five series tops that can say that.