[QUOTE=AmmyByNature;7049626]
Because (to get silly about it) the trainer is going to be expending 5/6th of those calories she’s eaten helping Daddy Warbucks, and using 5/6th of that rest she got dealing with Daddy Warbucks.
I (and lots of other people) won’t go to a show with just one other person or by myself - it’s just too expensive.
It makes sense for 5/6th of the trainer’s expenses to be paid by the people using 5/6th of her resources.[/QUOTE]
I don’t buy it. If she were eating more or sleeping more because of the extra horses, sure. But she’s not.
To me, that kind of reasoning sounds like a way of justifying a cheaper bill for yourself. I mean no offense by that, but that’s how it comes across. Sure, Daddy Warbucks can probably afford to pay more of the bill because he’s paying fr five horses to show, but ethically, I’m not sure that he should have to.
This coming from a broke one horse woman. A Sally Small Bucks, you might say. 
ETA: At the end of the day, trainer will do whatever trainer sees fit, and that’s going to vary. As clients, we need to be on board with whatever trainer decides, and if we aren’t, we need to figure out if it’s worth it, because ultimately it is their decision.