Too many variables.
Stock/Chassis
Action
Barrel:
twist rate, length, material
Bullet:
Type, weight
Powders:
????
Brass
???
Primers:
??
We have a .260 Rem that shoots a 123gr, 130 gr, 140 gr, 142gr (H-4350, BR-2) all in the same POI without changing anything on the Scope. Just lucky to have produced loads that matched. We can take four different .260 cartridges to the range, have the scope set at 100yds and then put the ballistics in for any loaded bullet.
I may be missing the point but "Easy to Load" 'Fussy" "Not Fussy"
I know some shooters that say 6mmBR with 31gr of Varget and 105 Berger Hybrid. (bullet seating, brass, twist rate, barrel length).
Since the internet we just look at what other shooters are doing for a particular cartridge/bullet/powder and Manufacture Load Data and start a load workup. I don't try to re-envent the wheel.
There is no magical equation. It takes knowledge, experience, and work!