Re: Have you checked 14 boxes under system preferences...
Well fortunately I'm still running High Sierra… hoping that a small bonus of Covid-19 might be the release date of 10.16 gets pushed back to allow a few more months of security updates for my version before I have to decide what to do.
The problem is if you also have to time buying a new Mac right if you want the OS to be as stable as possible - i.e. ideally just before a new version comes out and the old one is still installed on the system.