Depends a lot on what kind of user. I specified “non-technical” with a reason. I have, in the past, recommended Ubuntu to a small number of friends and family members. These are people who aren’t particularly comfortable using computers in the best of times. They very much don’t need the newest, best and most shiny versions of everything. They need to do billing, taxes, correspondance, email and various other tasks related to their small business, they need that to work reliably, and if at all possible, to work exactly the same way as it did the last five years. And if there is any pop-up they don’t immediately understand (for example because it’s in English instead of their native language, yes that still happens in Ubuntu quite a bit), they will call me on the phone.
I don’t know if you’ve ever had to support non-technical end-users, but for some of them, even something as seemingly trivial as a menubar that has moved from the top to the side can be issue that needs explaining and training. For that kind of user, I really do want to postpone all updates beyond pure bug and security fixes for as long as reasonably possible. Five years sounds reasonable. Six months does not.