I have seen in many videos that some people deliver a Yokomenuchi stepping streight into Nage delivering a strike starting from the side of Uke's head and landing to the side of Nage's head.
Now my question. In both cases the final destination of the strike remains the side of the Hgae's head, but the position of Uke's body is very different. Will this deeply effect the technique to apply?
Ummm, okay I'll try to take a stab at this one (pardon the pun)
From my understanding.... the MOTION OF THE ARM
/sword in shomen-uchi and yokomen-uchi are the same; that is the strike begins at the TOP OF THE HEAD. This is or two reasons.
ONE: the strike has the optimum power of your hips driving it through uke (think about the sideways motion stike... almost baseball bat in its style... its driven by the shoulder and back muscles, which is not as effective)
TWO: the basball bat style strike is pretty easy to read and since its not centered from the hips its easy to counter
Now, the MOTION OF THE BODY
is where the difference is seen. In my experience, SHOMEN-UCHI is direct... where uke steps in a straight line (as you described) to deliver the stike to the shomen
(front of face). While YOKOMEN-UCHI begins from the back leg... uke takes a step off line as the striking hand raises. Think of a tiny tenkan... .Now that you are "outside" the strike lands but this time its on the yokomen
or side of the face or temple. When we practice yokomen-uchi we aim to align with the diagonal collars of the uniform.
I hope that this info is helpful... and again this explination comes from my experience. I reserve the right to be wrong as you said above..."every Sensei has his own method to teach"
and each student thier own style.