Here's what it looks like with NaOH on my tank water.
1 Liter tank water. additions of 1.0M NaOH.
Initial pH 7.72
API:
8 drops green, 9 drops yellow
8 green, 9 yellow
Red Sea: 9.1, 9.1 (0.65mL titrant)
added 0.100mL of 1M NaOH so 0.1 meq/L
pH 7.92
API: 8 drops blue-green, 9 drops yellow
Red Sea 9.3-9.4 (0.67mL titrant)
added a second 0.100mL of 1M NaOH so total 0.2meq/L
pH 8.06
API:
8 drops blue-green, 9 drops yellow with a little green
8 blue-green, 9 yellow with a little green
Red Sea: 9.5-9.6, 9.5-9.6 (0.68-0.69mL titrant)
API instructions are "when it goes from blue to yellow", so you could choose to round all those results to "yellow at 9dKH", but if you look at the colors, it's clear there's a difference, but something less than a full drop.
Red Sea Alk works fine for this. The 1.00mL syringe dispensing the titrant is plenty to pick up what is happening. Look at the target color on the card, average the titrant value when the color is just detectably "bluer" than the target color with the titrant volume when it's just detectably "yellower" than the target.
If it's done side by side with the product and NaOH, it should be clear what's going on.