You may get different answers!
I eyeball mine on the rare occasion I have to use any. But, I know my pool really well. I can usually even tell when I put the DPD powder into the sample water how much I'm going to need, even before I swirl it. My target FC is sufficiently low enough that if the test turns bright pink, I already know I'm OK. And if I need to add, if I am off one way or the other by much, it's so insignificant in a pool of mine's size, it won't matter.