Seriously - if your devices are on at least iOS 11.3, there is no pressing need for you to update, DON'T DO IT.
But it's not enough for only you to know not to update - you also need to tell your suppliers and staff who use Apple devices in your environments that they must not do so.
Only look to move on from iOS 11.3 if reports come through that iOS 12 has not brought with it any new problems, such as severely reduced battery life.
We'll be looking at this issue regularly, especially as iOS 12 updates keep on coming. iOS 11.1 was released on September 19th last year and while initial reports seemed hopeful, further issues arose for a wide range of users.Apple iOS 11.1 Starts Causing Problems
Newer devices seem to experience less issues, and are often improved - but for older devices it seems like bugs can be expected to arise.