Arg... I wanna be a part of all of your groups!!!
We have a player in our group who has just admitted that he
likes rules debates during the game. I'd go so far to say that he prefers them, but that's just my opinion, not his words. He's admitted to preferring complex rules systems when I said I had issues with Song & Silence needing 2 pages to handle garrotting rules.

Of course, he's
really good at math, so he can handle those kinds of systems far better than I can (He
loves Dangerous Journeys).
Unfortunately, every single time something comes up in the game that he doesn't like or agree with (flanking's stupid, it doesn't work that way in real life; Power Attack should be limited to 5 or the weapon's maximum damage, if a 20th level character catches another high level character unarmored he can cause too much damage) or any time we find with something vague in the rules, a rules debate starts. The debates don't even have to be strictly rules oriented. We recently wasted an hour debating whether or not an outsider (a nightmare) can be turned into a Vampire! I'm perfectly happy to trust the DM with his ideas and follow up on them
in game, but any time something different comes up, he has to argue about it, which in turn destroys any kind of mystery the DM may be trying to create with a cool new creature or idea. Unfortuantely, I allow myself to get drawn into them once they start, which draws out the debate even longer (since we both have very different ideeas on what's good in an RPG).
So how much time do we spend debating rules for every 8 hours of game time? At the very least 2 hours, sometimes more than 4 or 5 hours... (Never in his campaign though... the only thing that slows that down is his lack of preparation and the fact that he has the attention span of a fruit fly with ADD).