Your instincts are 100% correct.
You can substantially improve the life of most CV joints by repacking them.
Take my 2005 Subaru Impreza for example. an extreme case that makes this clear
The heat of the exhaust under the CV joint super heats the grease and it all spins out.
Yes, between the boot, where it is clamped, and the shaft.
There are no tears or holes in the boot. you can see where the grease was flung and cooled and piled up. A well documented problem that should have a heat shield or something.
And Subaru is happy to repack for $200 if YOU catch the problem ! otherwise they get ya for a $500 CV replacement later.
If you look inside used CV joints that are not torn boots, you will wonder where all the grease went? I suspect the above phenomenon happens on a lessor or over a longer period of time, to many CV joints. I heard one comment that boots crack sooner due to loss of lubrication inside. I think this is one of the auto industries dirty little secrets that
gets blamed on the eventual torn boot. I think heat degradation in CV joints, is more
rampant than the industry admits to.
I went from Honda to Subaru to get away from CV joint issues, and now this?!?
I'm thinking "hose clamp", instead of the original; so I can just keep pack'en er.