Oh my, this is a good one........ I like Barry am in the "old fogey" group. My body has been used/abused from the years on this earth. I go every 6 weeks to the chiropractor just so that I CAN ride. I go to the gym 2-3 times a weeks so that my muscles are strong which helps with the joint pain.
I've worked with several instructors over the years and one of the best was a lady who helped me ride well in-spite of my body. There are positions, like Barry, that I can not hold for any length of time. This lady helped me achieve a good seat because I'm a level boarding on up footed person. Trying to keep my heels down results in the complete loss of feeling in one foot.
You can still achieve that invisible line of shoulder, hip and heel with a level foot. You can still achieve a solid seat without your heels down. You can still maintain the correct leg position without your heel down. None of us have perfectly aligned bodies. I have one leg long than the other, and one hip is turned in which causes me to walk funny......Over the years I have had to find ways to compensate for my body.
I've spent years trying to hone my equitation skills and have some ribbons to show it's not too shabby, in spite of the fact that my body doesn't always bend the way I would like it to.
But this exercise illustrates only too well why the riding instructor takes the easy way out and calls "Heels down" - it is all too complicated for him/her to explain in a training arena.
LOL, I think it's more of a CYA sort of thing. If the kid falls then the instructor can say "I told you to keep your heels down"......
I tried to make this picture bigger to show my feet but I don't think it worked well. This is a grid clinic, jumps are very low. The purpose of the clinic was to work on body position. It's not the best picture, but I think you can see my feet are level, my leg is solid, I'm jumping with him and not ahead or behind him, I've given George lots of release and even though he's going at the jump like it's over 2 feet I think my position is very solid. I'll try to find some other jumping pictures on the computer at home.