The rythym section is the smaller jumps. I think there's usually anywhere from 3 to about 7. Too many to jump them all, too close to get a lot of pedalling in.

[edit] A track is all ups and downs. There's not always a flat spot to land on. Except for turning, there's really no need to have you front tire touch the ground. Also, a jump in racing is a lot different than a jump in freestyle. There's a lot of forward momentum, as opposed to just coming down hard.