At what point do you gas up?

So I got to thinking the other day, with gas prices the way they are how long are people waiting to fill up their trucks? 

Me personaly, I fill up when I need to, and I always fill it to the top. Which brings up another question, do you fill it all the way or just a little? Why? I hear people doing this saying gas is expensive so I'll only buy a little, but when you use 10 gallons a week it still costs the same weather you buy it all at once or a little at a time, never really understood that one.

So when do you fill  up? Do you wait until E or do it at 1/4? Do you even fill your tank? We want to know!