i'll be honest, i find myself "wasting" vapor hits sometimes. what i mean by "proper hit" is the full inhalation where you really expand your chest/lungs inhale deeply where you can almost sense the tingle and warmth all the way in your stomach, then really hold it in for at least 15 seconds. one of these hits of some potent stuff... and i'm f'ing out. ... but for whatever reason once in a while i forget all about this good technique and take tiny hits, where i don't really inhale properly and definitely do not hold it in long enough.
A lot of this depends on which vape you are using. As an example, I used a Purple Days as my daily driver for over 4 years. I would load up the stem with 0.025g and get 5 hits from it, no matter how hard I hit it. With my new LSV, I can load up 3 to 4 times that amount, and it will thoroughly cash the bowl in one hit, providing a SUPER RICH thick and voluminous vapor hit.
i've used PD in the past... and absolutely love it. probably well over a year. actually it's a good example, out of the 5 hits i sometimes take one really good one, and 4 mediocre ones, because i forget about good technique.