The short answer is you don’t need to make the rescue media every time you backup.
I’m kind of surprised that Macrium is updating itself that frequently. It’s OK, but the important thing is that you are not required to make a new rescue media every time you back up or update the software.
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Yes, there is a small risk.
The risk is that at some point the backup software will update itself so the format of the backup changes somewhat. That format change could cause the rescue media that you made six months ago not be able to understand the backup.
It’s not a disaster. If that happens, find another machine, make yourself a rescue disc right then and there with the most current edition of the software (in this case, Macrium Reflect), and use that recovery disc to restore or recover from whatever backup you might have.
With Macrium, the good news is that the rescue media appears to be completely backwards compatible. So it is theoretically possible to never make a rescue media until the day you need it. The only thing you need on that day is some other working computer with a CD burner. You can then download the Macrium Reflect rescue CD and burn it on a working computer and then take it over to whatever machine is having problems.
In my case, I make a rescue CD when I initially install the software and I squirrel it away in a (physical) CD/DVD folder. In my world, when you need a rescue, you don’t really want to take that additional time. You’re kind of panicking; you want to have things back the way they were as quickly as possible. Having a rescue CD ready to go is one way to avoid that little panic.
But if you don’t have a rescue disc, just find another machine and make one. You don’t need to make one every single time you update the software.