For us Paul we have 5 sets (Burris 33 only rule)
Each set Rr,Rf,Lf all measure the same, only difference is the duro.
We have 15 LRs, 3 per set matching duros, this is the tire we adjust not only stagger, but how the kart reacts coming off the corner, too soft can cause a push, and too hard can cause a loose condition.
Most new karts are designed around using 3 tires equally, and no you don't have to run the same duro on each corner, most will run the lr same as the set, and adjust the kart.
My thought is to adjust the grip before chassis changes