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I did a comparison test once.

I loaded 2 batches of ammo with identical cases, charges, primers, bullets, & so on.

one set was trimmed for length, chamfered & deburred then loaded on a Dillon RL450b with no other things done, the other was also primer pocket uniformed, primer pocket cleaned, flash hole deburred, cases & bullets were weighed & segregated by weight, & cases by volume, then single loaded on the same press & dies.

Then I shot for group at 200yds, off a bench & bagged, so it was only the rifle & load determining the accuracy.

There was no practical difference I could find either from chronograph readings or group sizes.

I quit doing that afterwards.

However, your confidence plays a big role in accurate shooting, especially when shooting “in position” (not off a bench).  Some shooters will weight powder and bullets because it gives them the confidence that their loads are perfect.  Any doubt that creeps in to your head will show up on the target.  Yet I know many of the best Service Rifle shooters do not weight powder or bullets, they don’t waste their time in it, time is better spent dry firing and life fire practice and match shooting.