Honestly with such a potent compound I would never trust a single dropper, but I don't really know how much a drop can vary, and true it is unlikely that a single drop of liquid could come out as 3-4mls as that's a fair amount of fluid when compared to a drop from a dropper bottle and they probably don't vary THAT much, but what happens if you don't notice that you squeezed quickly or something and it was several drops or something instead of the intended one drop (especially if you're putting a single drop under your tongue or something)?
Seems untrustworthy to me but definitely better than some person playing with eyeballing powder for sure. So in the sake of harm reduction it's definitely WAY better than eyeballing powder, but just make sure you're taking a consistent single amount, and you might want to drip it onto a small something not absorptive to make sure it looks like a consistent amount and then suck it up.
Really, it would be better to measure out several "single" drops in a oral 1ml syringe or something and see how much they vary just to be sure, or find a supplier that supplies it as mg/ml OR better yet find a supplier that sells powder and buy a mg scale that you can put a calibration weight on several times and see the same calibration weight amount come up, and then read up on making safe volumetric solutions NOT in ethyl alcohol or another alcoholic beverage (I.E. polyethylene glycol, though really if you're making a .5mg/.1ml solution and measuring it with said 1ml oral syringe and NOT doing more than 1-2 mg it should be safe, but I just never think making volumetric solutions of benzos in alcohol is a good idea as a rule of thumb).
