I agree, that is my problem as well. Mostly because at any given time the person practicing will never know how much of what he is using would have been negated later in the system if the teacher knew enough.
Only thing we know is the practitioner will have holes in their method all through the time they are using the system, suggesting at any point on important question the system may fail them...
So its creating a construct that by definition is unstable when done this way. It seems to have resulted in a lot of people thinking WWG is unreliable... Yet that isn't because that is inherit in the system, its because the people that wrote about it(some of them , anyway) wrote in a way where a false methods were given, then much later on parts of them negated... And that continue each step of the way.
How much he never had enough experience to negate and was left in there as a potential trap for the practitioner... All that someday will backfire usually in a small way, leading to people losing faith in the system, but in some cases may actually be in big enough way...
That is one of the main reasons I really dislike Wild Cranes material. Practicing by this, one takes a compromise, they will adopt not fully working rules, hoping sometime in the future they will "repair" them... If that happens, great, but when there are a lot of those piled on top of each other, at some point its debatable how easy it would be to fix the system, even if fully working system is given. Then they have layers and layers of techniques with holes in them, as that was how they were presented originally...
So better ignore the material, learning by it is just a way of adopting weakness in the approach then piling more on top of that until they become impossible to find later on... And al that could be a real problem later on...