I have figured out that one drop does about two draws for me...so trying to keep count to avoid the bad taste.
How many draws you get per drop varies a lot. It depends on the type of atty (306, 510, 901, 510-t, etc.). It depends on the resistance (SR, LR, or HR). It depends on the individual batch of atties, the quality and accuracy of resistance of that batch from that manufacturer. It also depends on how clean or gunked up the atty is and on how old and worn out it is.
When I have a really good SR 306, I can vape on it for at least 10 minutes. But, that's when everything is perfect. Perfect atomizer, perfectly clean and working at its best.
If it's getting dirty, it won't last as long. One time, I got a bad batch of 306's that must have been a slightly lower resistance. I could get 2 or 3 puffs, then suddenly hot! I got rid of them.
SR 306 and 510-t drip better than most. Because they're standard resistance, they seem to burn up the juice more slowly and last longer between drips. And, SR atties aren't as likely as the LR to get suddenly hot. They're more likely to get a little dry first, but not too hot, too suddenly. That gives you a warning to drip more before any unpleasantness.
But, each individual atty will be slightly different.
It was just dumb luck that I stumbled upon the SR 306 way back when I first started vaping. If I had the bad experiences with them that I had later, I would have given up on dripping from the start!
Good luck, and happy vaping!