Scrubbing jumps looks cool but there is also some actual science behind it too. Keeping lower in the air allows you to scrub valuable seconds off your lap times. 

“It’s not about how much air you can get but instead about taking height away because in the air you lose speed, so the idea is to take off as fast as possible and carry that momentum across the jump,” says Jeremy McGrath.

Granted this video focuses on the supercross side of things but is relative to enduro and in particular timed card enduro and special test racing where every second literally counts. 

On this supercross test track there was a difference of 3.32 seconds between scrubbing and not scrubbing jumps.