Most servers (Apache, IIS...) have a 20 minutes default window. Unless I'm mistaken, it's been this way since the late nineties, as a middle ground: on one hand, it could be increased, but on the other it would be costly in terms of resources (each session has to hold a number of parameters in RAM, and also takes a modest amount of processing power), so it's generally frowned upon (by "frowned upon", I mean that if you post "how can I increase the timeout on server X" on StackOverflow, you can bet on getting 50 answers telling you why it's wrong, and none telling you how to do it).
IIRC, the server hit 70% capacity when VSTs were announced, so increasing the timer in a manner significant enough to make it noticeable would have probably caused drop-outs in this case. Kenni could probably increase the RAM capacity on the server, but he's doing all this out of his own pocket and I don't think the ads cover that much yet, so there's a limit here as well.
Page Back recovery (circa 2002/2003?) was/is a godsend indeed!
