Shedding.

[Rachie]

So, as far as I know, there's no specific season for snakes to shed skins.....I have 3 snakes 2 babies and a 2 year old. A Stimmy, a children's python and a spotted python and they seem to have synced up sheds. The 2 year old spotted python shed first (same day she ate)
My baby Children's python has begun shedding today and ate on Wednesday.
Now the husband's Stimmy baby is looking dull with smoked over eyes (was due today for feed, but not interested). I'm not concerned, I just thought it interesting.

 

[Vixen.]

They shed when they grow... you feed all same time, they grow at same rate, inevitably they will have a shed that overlaps with others. They shed most when younger, growing faster, but will shed for their whole lives and it's how they grow so there's no seasons.

 

[Rachie]

Yeah I know. I just thought it was interesting because there is no set season.

 

[Sdaji]

Yeah I know. I just thought it was interesting because there is no set season.

There are some seasonal cues for sloughing, and some hormonal cycling which gives it specific timing. Males will generally time their sloughs so that they won't be sloughing during the anticipated peak breeding season, females will do something similar and also they have a fairly consistent post ovulation slough, then another slough once they come off their eggs (if they are incubating eggs they generally won't slough but if you take the eggs away from them they'll usually slough before their eggs would otherwise have hatched).

Sloughing will often be triggered by air pressure changes or sometimes changes in humidity, and as Vixen says, if you're feeding them at the same time they're likely to fall into similar cycles. They can also synchronise according to cage cleaning cycles in some cases - I've seen about 30% of the snakes in a bank of racks slough within about 24 hours of the racks being cleaned (other factors also contributed to that synchronisation event but the cleaning was clearly part of it).

The timing isn't all exact so if you have a small number of snakes you may not notice it but if you have hundreds of snakes expecially if there are large numbers of the same species you'll see some synchronisation and it will correlate with feeding cycles, weather patterns, seasons etc. It's not unusual to have only a few sloughs here and there then have dozens within 24 hours.