http://www.tamingarchive.com/faqs/superstitions.phpSwitching Servers
Some believe that some servers give more skill than others. By switching servers, you can move from less populated to more populated servers and vice versa. However, skill gain was disconnected from shardwide usage back in early 2000. This meant that the more a skill was being used, the harder it was to raise. This is no longer the case.
So, during T2A was there some kind of skill-gain "pool" which meant that if a skill was being used more frequently on the shard then there was less skill gain to go around in that skill?
I seem to recall discussion/mention of this back in T2A but never fully understood it or its effects.