I hate to complain when everyone here has been very helpful. But when doing the oclt test I wanted to be sure my numbers were right so I did multiple fc tests and they come back different every time. The difference was more than 1ppm so the oclt test is invalid imo. I was getting between 20 to 24 drops. After testing 5 times and getting 5 different results I decided to save my reagent.
You're actually raising a complaint about the actual chlorine test, not the OCLT. The chlorine test is just a way to measure chlorine, but that doesn't mean the OCLT test itself isn't valid.
The chlorine test is not going to be 100% repeatable for many reasons. Someone above said the test has a 10% margin of error. That's in line with what you're experiencing.
Also, how do you know you're putting in EXACTLY 10 ml of water every time? That's a very small volume of water to get right every time. You could use a 25 ml sample instead, which would be easier for repeatability, but you would use way more powder and reagent.
And more fundamentally, there accuracy and repeatability are two entirely different issues when it comes to testing, which is a whole other topic. But I suspect what you describe involves both.