I say use as many sighters as you need, just be aware of your time limits. I always run several on a clean barrel just to get it to tighten up before I get serious about my sighters on the target. I use an extra target so I don’t accidentally put a first round flier in a record bull.
After the first target, it usually only takes about 2- 3 to confirm poi and start shooting record bulls, the ones provided on the match target work fine, if there is a delay, I will shoot a sighter or two to make sure I’m not getting a cold bore shift in the record bulls. The other day it was low wind and I shot 18 to acclimate and confirm a solid zero for my condition. My total round count on a 100 shot match was 145. If I get a bad shot. I will go back to the nearest sighter until I get a 10 or X.
I have shot 225 rounds in a very windy 75 shot match. I always make sure to have plenty of ammo from the same lot for whatever happens.
My friend shot 2 250- 15x targets the other day in a match, ran out of that lot of ammo, changed lots on the 3 rd target shot a 245-12x, found a partial box of his best competition ammo in the truck and finished with another 250-15x. If he hadn’t changed to a different lot, he would have likely won the match, as it was he was 2 nd by one point.
It’s always best to eliminate as many of these variables as possible prior to a match. Thats why I usually try to practice and work through these issues before the match. Often on the same range as the actual match to help foresee any setup variables or unique range conditions.