I'd also add that the reason some folks here wanted faster experience rates isn't just because they have LESS TIME to play WoW when they are able to sit down and play it (an hour versus three hours when they were teenagers) but they also have FEWER OPPORTUNITIES to actually sit down and play (only on Saturdays and the occasional Sunday versus every day when they were teenagers).
Drawing out the patch releases gives people who are busy with work, family, and other obligations more time to catch up with others. If the patch releases are too fast, then even with 5x or 10x speed such busy individuals might lag behind and quit out of frustration.
In my opinion, Vanilla should last a year minimum, but 1.5 years seems better given all the content. Likewise, each expansion should be 6 months minimum, with 8-10 months seeming a bit more ideal.