They aren't all working on the same timer, no. Animals are like that, where large groups of follicles work in unison (which is why they have seasonal molting/shedding). On humans, each follice starts it's timer at a different point of time, but each timer still gets set for the same AMOUNT of time. So - if hair 1 and 452 started at the same time, they should fall at the same time - thus the idea that you shed 50-100 hairs a day - that means that 50-100 follicles on your head are on the same 'schedule'. The other roughly 120K follicles though, are on different schedules, and if they are in the growing point, the other follicles resting/shedding doesn't impact them at all.