You don't have to install the latest and greatest however if you do encounter issues support will request you test the latest package to ensure the issue hasn't already been fixed in later builds. You can review the release notes of newer builds and make decision on if you want to install or not.
The ENS Updates are released every month or every couple of months - depending on what issues have been identified in the field and the urgency of any new features added. I wouldn't agree with your statement about "just leaving the last major version", purely because some major versions do have major issues which were then addressed in the monthly updates. Again I'd refer you to the releases notes and the Known Issues KB so you can review and make a judgement call.