Hi MR_IT_Guy and thanks for your reply.
The reason for my question is very similar to what you wrote, because I manage an Organization with more than two hundred switch and more APs and is not easy schedule a maintenence windows with final customer.
So, in many case I'must reschedule the upgrade (more than one time) or in others cases cancel the upgrade.
So I'would want be sure than there are not any downtime in the networks. For sure, I always try to keep updated all the devices of organization to the last stable release.
Thanks