I've standardised on 1.25 ml per "dash". And then I don't use the dasher bottle. :-) I found a soy sauce dispenser bottle with a button on top. You tip the bottle over and then press the button. To my amazement, 1.25 ml comes out, pretty much every time. It does drip a bit, though, despite the claim that it doesn't drip :-).

Here's an amazon link: https://www.amazon.com/Dripless-Glass-Sauce-Dispenser-Black/dp/B003OA41TO/ref=sr_1_9?keywords=soy+sauce+dispenser&qid=1650351099&sr=8-9

I live in Japan and picked it up at a housewares store for a bit less than what Amazon is charging (850 yen).