Agreed, one fear that can be overcome at Philmont is worry about there not being enough. It is true that water locations are extremely predictable. You'll generally know ahead of time which intermittent streams are flowing, which springs are not, and so on. You also know that every staffed camp will have water. So you're quite right, over carrying water because you're not sure if there will be any along the trail can easily be overcome.
I cannot stress enough however that, regardless of experience level, Philmont is not the place to push one's self to Make Do with less water. I agree with planning effectively. But it is a fine line to tread between effective planning and over exertion and under hydration.
Heat Exhaustion can happen to anyone, and indeed Heat Exhaustion and Dehydration are the most common forms of injury at Philmont. If you're hiking in certain areas, such as Abreu to Urraca Mesa, Harlan to Deer Lake, Indian Writings to Ponil, or especially if you're hiking any of the peaks, I would advise your crews to be very conscious of the water they carry with them.
If you ever say to yourself "no, I don't need to take a drink of water, because I need to make do with half a liter", then next time just double your estimate and take a full liter.
Hydration is too important. Other conditions can be more easily over come by knowledge and preparation. If you leave out that extra jacket, it's easy to not get hypothermia by wearing your rain gear, or change out of wet clothes so you warm up. You can avoid taking spare stoves by understanding stove maintenance. Just don't try to out think your body and do more with less water.