Interesting thread. The one drop per gallon dechlorinator I used for ages was discontinued 20 years ago, and I simply stopped dechlorinating for any water change below 30%. I was dealing was simple chlorine, and not chloramines. I bred 200 species of fish in that time, and all my fish were very long lived, so it was not a problem.
It worked just fine, but after I moved this city seems to go chlorine happy on an irregular basis. For those days (once or twice a month) when a swimming pool comes out of my tap, I decided to listen to people here and buy myself my first ever, 55 years into the hobby Prime bottle. My plan was to use it for one species that would not lay eggs fpr 4 or 5 days after water changes, in case that was the chlorine that didn't gas off, and to treat all tanks on the bad days.
It is a pain in the water butt to portion out given that I have small (10 and 20 gallon mainly) tanks. I can't seem to get the API product here, without an international order, and am stuck with the Seachem product. If I were to go over to using a dropper, what would you suggest for dosages, in US gallons, so I can waste less and put less of this into my water?