Positioning ballasts… how’s it done (correctly)?

Not a few think that the ballast should be "reviewed" in many categories, such as the OKJ, where 12-year-olds of 35-40 kg often have to push karts with 20/30 kg of ballast, an impossible solo effort in the case of an outing off the track. On the other hand, some might say that the weights in these categories, especially OK, are a bit low for those with a few extra pounds or centimeters, which is why many run onto KZ. Even the discourse of increasing the weights in the name of safety to "make them go slower" does not hold much, since it would make much more sense to act directly on the engine in this case (in addition to the fact that by increasing the weights the engine work or forces more, increasing the management costs). In fact, just think that the weight difference between a KZ (175 kg) and an OK (145 kg) allows lap times on tracks such as Lonato with sometimes a difference of only two tenths ...