My sims usually top out around +17
I am also curious about this: I practiced with Fred Renzey's ramp, and noticed I was throttling up fast, to the point of quintupling my bets on successive hands fairly often.
I have run a few dozen Mentor sims on CVCX and CVData, and I have never seen a ramp, for a spread of 1-8 or more on a shoe, which did not hit maximum bet at between 13 and 19, depending on rules, penetration, and Wonging strategy. For pitch, or lower spreads, it's different: some ramps on CVCX will top out at 12, or, if the rules are really weak, 11.
The ramps in Renzey's book seem to be set to guarantee a sufficient advantage at any game. It's just that they are quite aggressive for shoes with decent rules and penetration.
I recall simming with the given ramps: risk of ruin was higher, as were win rates, but not much in either case. They will get the money.
Picturing Mentor true counts as 1/4 a high-low count value is a serviceable summation of the equivalence between the two.
I'd be interested in hearing Fred Renzey's discussion of these ramps.