It explains that the rules kind of "break Down" after playing for a bit.
When you've played with a rule for a certain amount of time, however, the rule degenerates, so to speak, to the next rule in line. Thus, All will degenerate to Direct - the worst of the trading rules (thanks to Vilurum and Terence for explaining this to me)..
We've learned a few things about trading rules since Sister wrote the FAQ. Basically they can do one of three things:
1. Degenerate. There are two patterns for degeneration: one goes All -> Direct, Direct -> Diff, Diff -> One. The other goes All -> One, Direct -> One, Diff -> One. (One is the baseline, so it can't degenerate.) Without getting too heavily into the code, it basically switches between these patterns every 37-ish games or so (random factor involved, so it may be more or less).
You can find out which pattern is currently in effect by talking to the Queen of Cards and asking about trading rule. If she talks about a trading rule spreading out from a region then it's the first one; if she talks about people being conservative and heading for One then it's the second one.
Note that playing a game *anywhere* will have a slim chance of causing trade rule degeneration in any region, not just the region where you're currently playing. (Each region is independent, so after a given game you may get all eight regions degenerating - although that's massively unlikely - or you may get none of them degenerating, or you may get any combination in between.)
2. Imitate the dominant region. Merely *challenging* card players in a region (don't have to get to the rules screen) will establish it as dominant. The game code has a counter from 0 to 10. If you challenge someone in the dominant region, the counter is increased by 1 unless it's already 10, in which case it stays there. If you challenge someone in any other region, the counter is decreased by 1 unless it's already 0, in which case whatever region you're currently doing the challenging is set to the new dominant region. (Short version: if a region's not dominant, challenging 11+ times there is guaranteed to make it dominant.)
Anyway, after playing a game anywhere (similar to degeneration), there will be a slim chance - varying with the counter, I think the chance is highest when the counter's around 4-6 or so, lowest at 0-3, and moderate at 7-10, or something like that - that any region in the world will adopt the trade rule of the dominant region.
3. Imitate the Queen of Cards's personal rule. When you challenge the QoC, the rule she uses in that game is her personal rule. Each time you challenge her, it can either stay put, go up the ladder of rules by 1 step, or down the ladder of rules by 1 step. (So if she had been using One, she can use either One or Diff. If she'd been using Diff, she can use One, Diff, or Direct. If she'd been using Direct, she can use Diff, Direct, or All. And if she'd been using All, she can use Direct or All.) So you can challenge/yes/quit repeatedly until you get her personal rule where you want it.
After playing a game with someone in the QoC's current region (this can and does include the QoC herself, who will be in that region at the time), that region may change its trade rule to match the QoC's personal trade rule. (And from there, of course, if it's established as the dominant region, other regions may start to imitate it.) So what you do is you play/quit the QoC until her personal rule is something you like, and then you go play other people until they start imitating that.
Because Direct is generally considered evil and hateful, it's generally advisable to aim for Diff rather than All, since Diff will never turn into Direct and is just as good or nearly as good as All for cards if you win by a large margin. (And even a 6-4 win is still more cards than One.) --- - Vilurum Xaren, leader of the happy turtles, and knowitall. ... And if you can't spell "Vilurum", call me "Vil". :)