That's one of the things that drives me crazy about White Bass. The light switch on and off nature of them. Last year my Dad and a friend went and found a big bay off of a river and literally could not throw a bait in the water without catching one, they caught 100's on a Tuesday I think. We went on a Thursday and barely caught anything there. We had to go find a different group of fish.
At times, I know they are there, but they will not stinking bite.
Im really trying to find them staged before that start the big spring runs.