Well, I'll tell you how I know the policy I'm talking about is more popular than the one you're talking about: LTSes themselves, and vendors offering extended, enterprise support for old software in general and OSes in particular.

If enterprises would consistently and massively upgrade early (for example within 1 year of a new release), vendors wouldn't need to offer this super long support on such a widespread scale. There's a reason Windows Server is supported for so many years, or RHEL, or SLES, or Solaris, or whatever.