Over the years I've seen a massive difference in the quality of the actual person doing the balancing apart from the normal rim and tyre issues. The best rim & tyre pairing I've had came down to about a 1 ounce weight on each wheel and that was opposite the valve stem. The worst were tyres that were crap in balance quality plus out of round anyway. Once had an idiot who as each added weight didn't fix it he then would run it again and then add another weight elsewhere that cancelled the previous one and tried to fix it. Fortunately he eventually ripped all of them off and started again but I was ready to ask if either I could try or just take them elsewhere.
yes, I have seen that as well, the quality of the operator out strips the quality of the tyre some times.......... both negatively as well as positively
I used to buy my tyres way in advance of me putting them on to the car
gave me time to check the out of round, as well as where the heaviest spot was, prior to getting them fitted
used to do the same with my rims as well
now, I just stand there and ask "are you going to balance the tyre and the rim first - so you can match them up"
only ever had 2 people in the last 10yrs go - "of course mate - wouldn't do it any other way"
had a few look at me like I was speaking Swahili though............