@BrettS
By general health I mean effects on longevity and mortality, which apply to mostly sedentary folk. But it also might apply to someone who is primarily a strength and power athlete not interested in endurance. The research on this quantifies exercise by minutes per week and intensity quite modestly. It doesn't take much to get the benefits, or the point of diminishing returns. The only reason to do more is if you have performance goals that require more endurance or you just enjoy the activities.
I don't really know much about VWC, so can't comment much but in a general way. I understand it is a VO2MAX training protocol.
From my understanding and experience, Anna's comments are spot on. My experience in triathlon may provide a little additional insight.
Multi sport training is a little tricky. We'll discount swimming because it's a completely different kettle of fish. (Ha!) But running and cycling are both leg dominant, using the same muscles, but with different movement patterns.
Generally, it's accepted that the opposite ends of intensity cross over from sport to sport. So base training and VO2MAX Max training in one sport will benefit the other, probably because they both derive many of their benefits from circulatory and metabolic adaptations. But sport specificity is still super important. Triathletes are fast, but not nearly as fast as specialists. Lance Armstrong's marathon experiences are another example. In the middle Zones of intensity, tempo, LT, etc. are very sport specific, and that is where is the action is. Those are race intensities.
So would something like VWC, with its VO2MAX focus cross over to another sport, like MTB racing? I've often wondered, and I think the answer is maybe a little. The problem, aside from sport specificity, as Anna observed, is that high end fitness develops quickly and fades easily. I don't see why someone would want to try to train that quality outside the specific sport. Too much risk.
But maybe someone can't train the primary sport, but does have access to KBs. Could they replace some of that fitness? I don't know.