There are companies who will view this unfavorably if you are outside of rotation.
For example if there is a 3 month rotation on the shop and you and your shopper buddy do the shop in July, neither of you would be eligible for the shop again until October. Not all companies are like that, I've just heard rumors that SOME companies view it that way. I suggest checking with your scheduler.
There are reasons that a body stays in motion
At the moment only demons come to mind