The first bottle of MMS1 I bought, about 2 1/2 years ago, had the directions of using 2 drops of 10% citric acid or lemon juice for a 3 minute activation. I'd already read Jim's "Breakthrough," and so knew he recommended 5 to 1 ratios, but the 2 drop instructions made me curious. My experience was that it seemed that 3 drops activator to 1 MMS created about the same signs of activation (color of the activated drops). Subsequently, I generally used a 4:1 ratio for my own medicine.
With the 50% citric acid, my personal observation is that 2 drops of citric acid to 3 MMS creates a very similar level of the dark yellow color of activated solution in 20 seconds. For a solution for eyedrops, I definitely prefer to use 1:2 citric acid to MMS, as I don't want the acidity going into my eyes. When I do this, I wait 30 seconds for activation before adding water.
I talked with Jim Humble about how research needs to be done on all of the parameters of activation, and he agreed completely. There are many questions, such as: how much does the activated solution continue to release chlorine dioxide after it enters our bodies, our bloodstreams, etc.; how much sodium chlorite is broken down into chlorine dioxide per unit of time; how much chlorine dioxide remains in our bodies (or in an activated solution in water or water and juice) over time, etc. It's obvious that over-activation is possible - if you do a 1:1 activation of MMS1 with 50% citric acid and leave it without dilution, in about 45 minutes the solution will be clear, free of visible chlorine dioxide in the solution, and in an hour it will have almost no odor of ClO2 gas.
So, grounds for speculation and further research. ps - The activation time also depends on the temperature of the solution.