I think all the companies listed above use the same method of lining up the yellow dot (the lightest spot on the tire) with the valve stem (the *assumed* heaviest spot on the rim). Their logic is this set-up will use the least amount of balancing weight and keep the unsprung weight and rotational mass to a minimum.
Their reasoning is the valve stem adds extra weight to a balanced rim. There are some flaws to this reasoning. The rubber valve stem does add extra weight to the rim but a metal hole has to be drilled out for the stem to fit in. Is the missing metal heavier than the rubber valve stem? That is hard to generalize. The second flaw to their reasoning is they assume the rim is equally thick throughout the whole circumference and perfectly balanced at the time of manufacturing. Due to the loose tolerances of mass production, this is not always the case. The thickness of the rim can vary quite a bit thus throwing off the balance of the rim.
In reality, the valve stem may not be, and usually is not, the heaviest spot on the rim. I have verified this with my own rims and found that the heaviest spot (which can be measured by balancing the rim only, without the tire on) can be as far as 90 degrees away from the stem. After finding the actual heavy spot and marking it with a permanent marker (like a letter X punch), I line up the yellow dot with that new point to minimize the balancing weight.
Another way to quickly find out whether the valve stem is in-line with the heaviest/lightest spot or not is to look at the balancing weight on a balanced wheel. If the weight is next to the valve stem or 180 degrees opposite of it then the valve stem is in-line with the lightest/heaviest spot. If the balancing weight is anywhere else beside those two spots, the valve stem is not the heaviest spot. Since the wheel assembly (rim, tire, brake rotors) has to be balanced anyway at the end of the tire installation, the alignment of the yellow dot is not critical; but if you want to optimize the set-up -- which is what we are trying to do by lining the yellow dot with the valve stem -- then finding the true heavy point on the rim and lining the yellow dot with it is the way to do it and not use the assumed heavy spot (the valve stem).