There is a long list of tweaks one can do to make better rifle ammo. The law of diminishing returns applies.
I think the single most important factor is that the guy who weighs his powder charge to the second decimal place is the anal kind of guy who has been mindful and meticulous on everything, including how the rifle is set up and how carefully he shoots. One could wonder how well he would shoot without all the attention to detail, and then measure the improvements.
My son used to make ammo for military and police applications, plus ammo for DCRA Target Rifle shooting. The DCRA ammo was made by taking the condemned CBC ammo and pulling the bullets and reclaiming the powder.
The brass was sorted by headstamp year. The ball powder was mixed in garbage cans to make it uniform. The ammo was loaded on a Dillon 650 with Sierra 155 bullets.
This is surplus Berdan primed brass. Milsurp ball powder, loaded on a Dillon 650 (with the Dillon powder thrower).. No weighed charges. No brass prep. No matching of load to the rifle.
20 shots at 525 yards shot from a rail gun.
1.8" vertical 0.36MOA
In my opinion it does not hurt to be fussy about loading. However, the most important part of the process is to make a load that matches the rifle. (Finding the node.) After that, performance will come from rifle prep and shooter performance.