Well, here would be my explanation for what is occurring for you Melisss.
I would have to say that it is definitely not along the lines of "office syndrome" being that shedding is an end product of growth in reptiles.
I would think upon extrapolating growth factors to find a cause for group shedding frequency being at the same time would be much more dependent on the fact that your animals all most likely have similar temperatures and feeding schedules.
Even if your specific animals all have different heating elements, etc. I would have to say that just the simple fact that you heat/cool your entire house would mean that they all are being kept at a relative similar ambient temperature. Sure they all are going to have a difference in the temps of their basking areas but the normal temp that they are living within is probably very close within each of their cages.
As temperature in reptiles (all cold bloodeds for that matter)relate directly to the speed of digestion, growth etc then this would help to get a little bit closer to understanding this phenomenon.
As far as feeding schedules, most likely as with most other people taking care of herps you are out of convenience buying their food at the local pet shop on the same days, or if you feed pre killed, then it would be much easier to thaw out several at a time and feed on the same day, with close to the same regularity.
So in summary, I think the relation of similar eating schedules and similar relative ambient air temperatures (room temp.) would be what is causing this shedding frequency among your herps. Could be wrong but seems like the simplest explanation to the phenomenon that you and others are experiencing.