My advice to novices?
- Learn FreeNAS while testing your hardware and deployment procedures using the currently available RELEASE.
- Document all the steps.
- When ready, check whether there is a newer version, if yes, then grab it.
- Deploy the latest available RELEASE on a clean system (do not upgrade FreeNAS).
- If anything is not working as you had seen it, go back and deploy the version you did your tests on.
My advice to veterans? You are a veteran, since you have your own ways.
My ramblings on the related topics are below the divider. Read at your own risk

=====================================================
Non-IT users tend to go 100% for the latest/current RELEASE. So each of the releases should be made with an intention to be more stable than the previous one.
Those with the IT experience do some checks first, whether:
- there are development versions (and FreeNAS has alpha, beta and sometimes release candidate)
- there is a reasonable plan for the future (and FreeNAS has a plan for a 9.2.2)
- there exist a support community with both announcements and discussion about them

Unless an IT person has some specific needs (in my estimate that would be less than 10%, you know who you are ;)) they go for the current RELEASE, too. Reasons are many. However, if one is not a masochist with plenty of spare time, then not only a pleasure, but also the greatest benefits are obtainable when working with a version that has less, not more, bugs.
There are insane people everywhere, including IT..., but unless one is an IT manager, then one goes for the latest RELEASE to get less problems, and not more. Mistakes/bugs/problems with the upstream code¹,² do happen. So they are getting fixed... And I hope that 9.2.1.5 will be another step in that direction. With 9.2.1.6 and next ones to follow. I tested that for my very limited home use needs current RELEASEs (yes, the final „s”! :D) are acceptable. However, if any project announces features that are not fully available in the current version that is unacceptable! Especially if there is no announcement (that is a prominent warning in the release notes), that the situation is only a temporary one and going to be fixed very soon. I am talking here about no warning about
https://bugs.freenas.org/issues/4628 in release notes for 9.2.1.4 and for that release that never was...
¹ FreeNAS is on the current Netatalk 3.1.1, while even Wikipedia only knows about 3.1.0 :)
² FreeNAS is on Samba 4.1.6, with 4.1.7 released only a week ago; but 4.1.7 has plenty of bug fixes...