Same rules, multiple folders

I found a couple of topics along these lines but not with an answer which I think applies to my situation.
I have worked out a reasonably complex set of rules to grab images off a memory card and make copies on my internal drive in multiple locations. Now I'd like a way to simply apply that rule set to all my other memory cards (each has a different volume name).
I could just copy the rules, but I know they will change in the future, both in terms of which memory cards will be processed, and also some aspects of the rules will change due to other factors. So having them defined once would be very beneficial.
Technically, all inserted memory cards will come under /Volumes so I could use the subfolder approach, but it makes me nervous to have Hazel monitoring EVERYTHING on my Mac and I shudder at it navigating down all the subfolder trees (which my rules need to do) on any volume that's not a memory card.
Any ideas?
I have worked out a reasonably complex set of rules to grab images off a memory card and make copies on my internal drive in multiple locations. Now I'd like a way to simply apply that rule set to all my other memory cards (each has a different volume name).
I could just copy the rules, but I know they will change in the future, both in terms of which memory cards will be processed, and also some aspects of the rules will change due to other factors. So having them defined once would be very beneficial.
Technically, all inserted memory cards will come under /Volumes so I could use the subfolder approach, but it makes me nervous to have Hazel monitoring EVERYTHING on my Mac and I shudder at it navigating down all the subfolder trees (which my rules need to do) on any volume that's not a memory card.
Any ideas?