Travel speed in the Shadow Plan (maths are involved)

[Nuclearun]

Somewhat involved question:

Is there a set speed ratio between the Material Plane and the Shadow Plane? Shadow Walk says that you step into the Shadow Plane and you can move at ~50mph, which is about 16 and 2/3 times faster than walking on the material plane. A light horse can travel overland @5mph, ~65% faster than a person. Does this mean that if you took a horse with you when going to the shadow plane you could travel the equivalent of about 83mph on the material plane?

Similarly, if you had wings, or a flight spell that allowed overland flight at about double speed, does that mean you could easily travel at an equivalent speed to somewhere between 100 and 145mph on the material plane(overland flight specifies 48-64 miles in 8 hours)?

Finally: if you were... say ten miles up and falling (ignoring issues like cold, pressure, and breathing), could you shadow walk, continue traveling at terminal velocity and consequently fall at the equivalent of ~2000mph? (terminal velocity ~122mph, difference in speeds between planes are ~17, 122 * 17 = 2074).

Not sure you'd WANT to shadow walk in the falling scenario since you'd likely end up going splat much faster (1/3 of a minute vs 5 minutes of fall time). It also brings up questions about conservation of momentum when transitioning, but for the sake of argument I'm going to assume that dropping in and out maintains the PC's 'Apparent' speed as they would perceive it. I.E. walking people walk out, instead of flying out like they were hit by a car going 50.

Thoughts? Arguments? Other posts that relate to this question (I can't seem to find any)?

[Gray Warden]

Shadow Walk wrote:

In the region of shadow, you move at a rate of 50 miles per hour

The spell doesn't say that you can move up to 50mph, but that 50mph is your rate of movement. To me this means that, rather than walking along a shadowy corridor, you are being transported passively, as in a wormhole. This is even more evident by the way the spell is stated:

Shadow Walk wrote:

You and any creature you touch are then transported along a coiling path of shadowstuff to the edge of the Material Plane where it borders the Plane of Shadow

Notice the passive form. This way, it doesn't matter if among the people being transported there are differences in base speed; there is no involvement of waking, flying, double-moving or running: the whole group travels at 50mph.

[Garretmander]

Shadow walk is different than travelling on the shadow plane. Shadow walk travels at 50 mph.

If you are 'fast travelling' on the shadow plane via two somehow accurate plane shifts or gate spells, you tend to move at the speed of plot, but always faster than if you were on the material plane.

[Nuclearun]

Thank you folks, much appreciated.