There are a few games that I find very intense, i.e. when I'm playing them I get extremely involved and find myself on edge. Examples include Pick Two, Taj Mahal, St Petersburg and Domaine. These are great games, no doubt, but I don't find the same thing with other (allegedly) great games such as El Grande or Cosmic Encounter. I don't know what the difference is, I guess it's something in the mechanics intrigues me and sucks me in.
Anyway, the problem is that I find some of those games, in particular Taj Mahal, to be so intense that it's exhausting. In a given evening, I can only play one game of Taj, and sometimes I look at it on the shelf and think "No, I can't face it this evening." Having to teach the game first, which is almost always the case, makes it even more work. As a consequence, I will often put something easy to teach like Metro or Qwirkle in the game box instead of Taj.
So what should my rating for Taj be? A game that is totally awesome but I can't always play? I'll always play Metro, so should I rate it higher than Taj even though it's clearly a lesser game? I've bumped my rating for Taj up to a 9 nevertheless, as I feel I should rate the game on how I feel about it in the right situation, i.e. when my blood sugar levels are right and I've had plenty of sleep.
By the way, playing Pick Two with me is intense for everybody. In case you haven't played, there's a large pool of letter tiles. Each player starts with 8, and needs to arrange their tiles into a valid crossword formation. When someone achieves that they say "pick two" and everybody takes 2 more tiles, and they rearrange their crossword to add them. When someone has achieved that, then they say "pick two". And you keep going until the tiles run out, and score (negatively) for the tiles you didn't fit into your crossword. Speed word games are my forte, and I like to keep the pressure on, so my opponents find it hard work. Some people admit there's no point playing against me... but I don't care because I am in the zone when I play and that's a great feeling.