I stand up on steps to eliminate the need to flex the other hip and go as far as a neutral spine will allow.
Yeah, but isn't keeping the hip flexed and the knee extended on the inactive leg a big part of the challenge?
Yes, definitely. It's half the battle.
I used to view the pistol as the ultimate progression in single leg work. I think I got so caught up on the "challenge" aspect of it that I overlooked the "benefit" aspect. I think the biggest benefit is the single leg unsupported stance (meaning the off leg is not planted or hooked anywhere), essentially challenging you in all planes and therefore really calling out your hip and torso stability, and motor control.
The more time goes on the more I develop my training principles and the underlying principle is the "joint by joint approach". So, with everything I do I ask if it complies with "joint by joint". When the lumbar spine flexes, the exercise doesn't comply. It's not black and white and there are exception but that's when I ask, "can I get the benefit (single leg unsupported) elsewhere without the risk (lumbar flexion)". The answer of course is yes, if we modify the movement. This also takes us to single leg deadlifts, which are now my "ultimate" single leg progression. It's single leg unsupported and, you have to flex the down hip, whilst extending the rear hip, whilst keeping a neutral spine. I think a well performed single leg deadlift represents the "ultimate" in balance, stability, and motor control. It's also hip dominant vs knee dominant and, with most people, I don't see much of a need for emphasis on knee/quad dominant movements, since their movement is normally dominated by this in the first place and we really need to get more posterior chain work in.