I would think your mileage may vary also, depending on how deep the pool water is. If more shallow, say 3.5', you'll get more of a push with your legs and more velocity, therefore longer glide. If the water is deeper, say 4.5', you'll not have as much traction on the bottom to push with, so your glide will be less.
I think the assumption is that when one pushes off from the side when in the pool is that the feet push off from the side and not the bottom. Thus it does not matter how deep the pool is.
How high on the wall the push off is can be played with and the spot can become standardised.
May we swim with ease at the speeds we choose.