The situation you describe illustrates the major point that is often overlooked. Child support is often used as a smokescreen when what we really should be discussing is the welfare of the child. People often apparently take the position that child support and child custody are equivalent.
They’re not. Since they are not the same, it is pointless to try to create a “reasonable balance” of payments to compensate for time. And it is this confusion of child support and child custody that gets carried over when determining what actually is in the best interest of the child(ren). I’ve seen and heard of this often; a parent goes to court fully believing that once the judge learns about how the child is treated and the environment s/he lives in, surely the only course of action will be to move the child to more healthy surroundings, right? No.
Somehow it turns into a discussion about money, and the parent’s motives for even bringing up the issue are cast in doubt. (I.e., the only reason they are putting up a fuss is to avoid paying child support at all to the no-good worthless ex.) And to teach them that the court is not to be trifled with, the child support obligation is increased.
From the cases I am familiar with, I can tell you that the opposing attorney will not hesitate to use the potential of an increased obligation as a negotiation tool and a threat to discourage the other parent from voicing legitimate concerns.
If, however, child support was harder to get and shared custody was the norm, there might be less of this game-playing and everyone would have to find something else to hide behind and quit using children as human shields in the divorce wars.