uh huh. Most people who talk about coke purity have
nothing to back it up with, it's all sweet lies told to make them feel better about spending a lot for lactose.
If it's even 70% pure cocaine, a tiny little bump the size of your pinky nail should get you absolutely mashed...
Anyway, with good cocaine, you only need a little bit to get high. Doing too much, like Scarface size lines, you'll get way too stimulated and probably have to sit down and not do anything for a little while... that or you'll freak out. So yeah, if it's good cocaine, you don't need to do more once you're high on it.
You'll need to do more in about 20, maybe 30 minutes, when the high wears off though