Sometimes you get lucky and get one that shoots everything great. I actually have a mini 14 in 6.8spc (customized) that shoots sub MOA with anything I run through it.
More often than not though there's just one particular bullet, one particular powder charge and primer that gives you maximum precision.
That's why long range fanatics spend so much time tweaking and tuning.
When developing a load it's not at all uncommon to just load 5-10 of each of a dozen different loads, bullets etc at a time and spend a day at the range just seeing which of them hits the sweetest spot.
When you find that perfect point, make sure you have enough similar components and enough powder of the same lot number and load as many as you can. Then you are set until you run out and have to try again.
Sometimes you get a significant variance between lot numbers of the same powder so having enough powder to just keep running is important.
When I was loading a lot I'd just buy several pounds of a given lot every time and then chronograph a few loads to see what variation we had vs the last lot.