Now I'm sure that this has probably been referred to before but my searching the forums has not yielded anything. I want to know whether I should recreate rescue media after every update or only when referred to in the release notes. What is the key factor that means you need to re-create the rescue media? TIA.

I wrote a reply to a similar question earlier, so I’ve pasted it below with a few tweaks:

Most Reflect updates do not have changes that affect the Rescue environment, so although it’s fine to rebuild after each update (usually anyway, barring any new bugs), it’s not necessary. If you keep an eye on the release notes, then Macrium almost always calls out changes that pertain to Rescue in red text, in which case you can decide whether to update your Rescue Media based on whether the fixes/enhancements are or might be relevant for you and your system. But if you don't watch the release notes, I'd recommend updating at least periodically as a best practice. As a couple of examples of Rescue fixes and enhancements, a V7 update a while ago fixed a ReDeploy issue that could prevent migrating from a SATA to an NVMe SSD. Some people might need that capability later even if they don't need it now. And V7.2 has much better support for DPI scaling (requires building Rescue Media on WinPE/RE 10), so if you have a 4K laptop display, you'll now actually be able to read text in places like the activity window, whereas with older Rescue Media, that text was microscopic, along with some other areas of the interface.

As a safeguard, you can of course also keep older Rescue Media build ISOs around for a while somewhere else just in case the updated Rescue Media turns out to have a problem, which has also happened in the past.

jphughan, you are Macrium!  cudos for u
thanks

To follow up on what JP said, what I do is I keep an archive of old Rescue Media ISO's from past versions on the flash drive I use for Rescue Media as a fallback.  I use a large flash drive, so there's plenty of free space for such things.  And the Rescue Media builder only deletes its own files and folders from the Rescue Media flash drive, so it leaves user files alone.  Unless the flash drive needs a first time format, of course, for booting.