Well, I'll expand on mine
Touch free presoak and wheel cleaner is the only thing I try to be a stickler about. My high ph presoak has a line in the sand and if you get below that line, it simply doesn't clean anymore. Using my titration kit ( all are different) the magic number is right at 20 drops. If I titrate below 18 it needs to be addressed. If I titrate over 25 I tip down. The same solution for tire cleaner is titrated to 30 drops.
On friction units. I titrate the same presoak used above to about six drops. I then use low ph strips to ensure that we are getting as much alkalinity off the car as possible using conditioners or low ph shampoos. I even just use an acid in the rinse water, again in an attempt to get as low as possible (preferably 6 or lower)prior to wax application. I am currently titrating my tire cleaner to 30 but may lower that as the temps heat up because the friction unit is a bit drier process and the dwell is longer.
Self serve- I titrate presoak to six drops. That's enough where a customer can see a benefit of using the presoak as a "spray on rinse off" cleaning solution but its no magic bullet and brushing is still required on dirty vehicles. I don't normally titrate my tire cleaner in SS but if I did it would probably be 10-12 drops or so.
I try to titrate my touch frees weekly, but just like everyone else I get lax. I am much less worried about the friction units and really only titrate SS when I change tips or products.
As mentioned above by another poster- PH is way too vague a measurement for touch free cleaning. If you're not titrating your touch free solutions you're flying blind, and measuring by ph is not much better. I've experimented before and have diluted a touch free solution 50% and the ph was virtually unchanged, yet titration dropped by half.