Well, under normal circumstances, I will only ride a coaster a max of twice in any given day. There have been a few notable exceptions;
Top Gun: The Jet Coaster @ Carowinds - I rode this one once in the back, once in the front, and a final night front seat ride (AWESOME).
Villian @ SFO - I rode in the front, then in the front again with Thrillerman, and since the ride was about to close, we snuck in a final backseat ride (which was suprisingly less painful ;))
S:ROS @ SFA - Well for the Coaster Zombies SFA Invasion, Wild One and I rode S:ROS about 25+ times without getting off. We would simply change seats every so often, like a "Fire Drill". Thats also how I discovered that seat 2-2 blue is my personal favorite (left side :))
But for the most part, I'm with family or friends and none of them are into stuff like that. I have to admitt, I was getting a little bored after about ride 17 as well. However, I am SO looking forward to SRM. With two coasters, there can be a little variety =].
lata,
jeremy