As you're being somewhat vague (or at least in-precise) on what updates you're going to do, I'll make some broad blanket statements that will hopefully answer your question.
For windows updates on Servers
You can generally safely postpone the updates indefinitely, not taking into regard that it is not safe to have your system be behind in security, stability updates and bug-fixes etc...
As long as you don't reboot, the following is true:
- Your update is not / partially in place
- Your system is slightly more unpredictable
- Your next reboot will take longer, so an unexpected reboot during business hours might be worse than usual
While it is rare to have any averse affects after installing updates but not yet rebooting, it is still an extra degree of unpredictability that you should try to avoid.
Most people wait to install upgrades until they know they can safely reboot afterwards.
Keep in mind SP or CU installs are much more impact-full, and the reboot should not be postponed on those if you can help it (if even possible).
For middle-ware updates
This is completely out of your hands.
Each piece of middle-ware is different, and it depends on the vendor, as well as the specifications of the update.
If you're updating certain middle-ware to a higher step of the same main version most of them don't really require much in terms of reboots.
However if you're installing a new major version, some middle-ware will require a reboot, and be inoperative until you've rebooted.
The best advice I can probably give you is:
- Test your updates
- Make sure you have maintenance windows available for your updates