[susan53]

You can't really say that they are/aren't "correct" - just more or less likely. The difference between them is really one of speaker perception - does the speaker perceive the situation as being one with a series of individual items (in which case each will probably be chosen) or as a single group - in which case every will be used.

You can think of every + singular as equivalent to all the + plural. So eg I could say We've won every game we've played this season or We've won all the games we've played this season. Here we'res not thinking specifically about individual games but of them all together as a group - the group of games that make up "this season".

But given the right context, that might change : We've had some really difficult games this year - the first was against Redstone Ravers - and they're the league champions. The second was in January, when four of our best players had the flu and couldn't play. Then there was the one where we were up all night because our plane was cancelled and we had to play without having slept... But we never lost - we won each game.

Here the speaker is thinking about the individual games and so chooses "each".

So it's not a "rule" but a matter of speaker choice. How does the speaker want to view the items? That's why, as you correctly say, both often have an equal possibility of occurring: Each/ Every time I see you... This doesn't mean they're "interchangeable" though - just that the speaker perceives the events in one way or the other. Very often there's a 90% probability that, given the context, the events will be viewed one way rather than the other - which is why either each or every becomes much more likely, as with your example of every game this season. As I said, it's the use of "this season" that turns them into a group.

As another example, each would be much more likely in:
Don't just throw those books into the box. I need you to wrap each book separately (The speaker wants to emphasise that the books should be treated individually).

So forget "rules" and think about meaning and speaker perception of that meaning.