The quantity of vapes per squonk varies greatly by a lot of different factors. The 306 uses more juice per fire. The LR attys as a whole burn hotter and use more juice. The way you vape will make a difference, a longer vape uses more juice. The suction during the vape can also effect use of juice.
So, with that being said, I will say it is totally up to your vaping style and atty.
I will also say this. I have found that the best, most flavorable vape seems to come right before the burned taste. That wonderful vape makes me want to hit again, and then Yuck!!! Time to squonk!
The blind squonking works best for me, draw while squeezing, when you feel resistance and here the gurgle stop squonking!