I use 4 drops. I can't really make 5 drops work. This is my process for picking the color. You can skip some of these steps as you get better at it.
First, I work indoors, so I can get consistent results. I can't rely on outdoor light for that. I hold the comparator below an under-counter LED light strip. In the other hand I hold a white card 3 or 4" behind the comparator, at an angle between the comparator and the light source, sort of reflecting the LED light off the card through the squares of the comparator. If I'm having trouble with the color matching, I might alter the angle a bit to help.
I start at the bottom (though from the top works, too). I look at the 7.0 color, and then the color of the sample right next to it. I ignore all but those two squares. I ask myself, is the sample "oranger" or "pinker" than the 7.0 square. In your example, it's pinker. I move up to 7.2, the sample is still pinker. 7.4? Sample is still pinker. 7.6? Getting close, but the sample is still just a tiny bit pinker. This is where I might tweak the card's angle a bit, to confirm that. Then I look at 7.8. The sample is very close, maybe just a hair more orange. I double check by going to 8.0, the sample is definitely oranger than 8.0. So... pinker than 7.6, Oranger than 8.0. Tiny bit oranger than 7.8. I would conclude 7.7.
Say it was pinker than 7.6, but I couldn't call it for 7.8, and it was oranger than 8.0. Then I'd go with 7.8. For some reason, judging each color one at a time like that, without looking at the whole scale, not even the adjacent squares above or below, works for me.
In your picture, had you used 4 drops, this MO would have been even easier.