My cartridge list is simple :
Not an 'between' caliber guy. Have enough 'fun' handloading the above list and plain don't see a need to add to it. In fact, I could 'back off' and just have .22 and .45 Colt .... But then I do like the .44Spec... And the .357 is nice to plink with once in awhile (or when the wife wants to do some easy shoot'n although lately she likes to shoot her little .22 Bearcat ) .
Note I didn't list .38s because I don't own any .38s or plan to. So I will load down .357 cartridges to .38Spec power levels for general shooting. I do own .44Spec only revolvers, hence .44Spec in the list.... Plus my Ruger .44Spec flattops will handle loads to do just about everything that needs doing. Really if I was to remove one from my list it would be the .44Mag as what the .44Spec can't handle, my .45 Colt revolvers can ....
For the most part, the list is a personal thing, as well all see cartridges a bit differently I think.... and justify each one