The format of the 508 is unique in that you are required to ride from time station to time station. You are not allowed to change riders between time stations. Depending on what stages you do will determine how long you're on the bike. The overall times are slower (I think about 3hrs) than they used to be in the old (similar to RAAM) format. They are still faster than the solo riders though.
RAAM is a whole different animal. We're out for maximum speed so we're on the bike for a much shorter time. Every team is different but the fast ones have the riders in a four bike rotation doing 30 minute maximum pulls. We're basically doing a 30minute TT followed by a 90minute rest then back on the bike again. We do that all the way across the US. At night we do one of two things. We'll switch to 45 minute pulls or we'll have two riders doing 30 minute pulls for a few hours while the other two sleep. I prefer the latter. On the climbs we shorten the pulls to as short as 1/4 mile. On the descents we let the riders go as long as their speed is hovering around 30+mph.