It is generally preferable to run updates on your server as soon as possible after they are made available. This is particularly important if when they are security updates. In most cases, you can just schedule these updates to run during off hours.
In some situations, however, your web applications or other software may depend on a certain version of currently-installed software, and updating may risk breakage. For those instances, you may want to hold off on updating. Unfortunately, holding off for too long could also cause security issues. The end of the year is therefore a good time to take a look at your software and see what is current and what is not.
If you have delayed updates for certain software, it might be a good idea to run the updates before the new year, especially if you are running a business website that is not very active at the end of the year. By waiting until the end of the year, you can also take time to test the updates on a virtual machine to make sure they will be compatible with your applications.
The end of the year is always a good time to check your server’s overall health, and checking your updates status is one of those important tasks that will ensure your server stays healthy.