Originally Posted by
2old
If you use three chains during that time, you still need to change everything at the end (or do your cassettes and chainrings last forever)? BTW, I got my steel middle rings from Jenson (Shimano = $10; still have one or two); chains were $10 - $15 when I purchased them; still have two; 9-speed Shimano cassette = $23 Amazon (still have two); small ring about $10, still have at least one. However, to reiterate, I just said the expense is minimal (total about $60 or so) and it's what works for me.
OK, add one more chain. I've never needed to change cassettes if I remember to swap the chain when it's worn to 1/16" "stretch", and I routinely get 30,000 miles out of rings (again, until I forget to change the chain on time). I can see you've got a stockpile of drive train parts from before pandemic inflation, though, so until you run out of those I guess your approach will work. When your stockpile is depleted I expect you'll suffer sticker shock.