We recommend to our On Premises customers that they also keep up with major version jumps in a timely manner. The effort is worth it, even if it always means a small change.
But there are companies that have to stay on a major version for longer for various reasons. When a major version reaches the end of its life, we will continue to provide security patches for up to two years after the release of the last minor version, as long as they are technically feasible.
However, we also strongly recommend that these companies replace outdated software with a new version as soon as possible.