This is the exact model I use in this post here:
The technique is to stay in line, or directly behind the SC head, it dramatically reduces fatigue/wrestling with the pressure feedback.
Also, cleaning from the bottom up is the way to go, not the top. Doing it from the top can let you miss parts with the run-off hiding it.
Best way is to literally walk the whole wall up and down I find. Treat it like a kerb, walk up, walk back - only a few more times!
You ALWAYS need to rinse the wall with the wand afterwards too. It doesn’t do the whole job 
