I can tell by you question that something isn't clear... yet.
You start with a concentrated product. Let's call this a stock solution. You then take a small amount of the stock solution and add it to your working solution. The concentration of the working solution depends upon what your target is.
MMS is a stock solution of 22.4% sodium chlorite.
5% sodium chlorite is a stock solution of 5% sodium chlorite.
Stock solutions are generally too concentrated to use directly and require further dilution.
Let's look at an example to put some perspective on this.
Let's say you weigh 80 kg and want to target 0.5 mg chlorite per kg body weight. Let's also say that you are comfortable drinking 1 liter of this solution a day.
A gallon is just under 4 liters, so let's round things out a bit and say that 1 gallon will be consumed in 4 days at roughly 1 liter a day.
To mix up a working solution using 5% sodium chlorite as the stock solution we need to add...
80 kg X target of 0.5 mg chlorite/kg = 40 mg chlorite in 1 liter. Since we have about 4 liters we need to add 160 mg chlorite to the gallon of distilled water.
With a 5% stock solution you add 12 ml of the stock solution to the gallon of water to achieve your target working solution. You then reduce the pH of your working solution to 5, add 1/4 teaspoon of non iodized salt, and let it activate for 24 hours. Then it is ready to go.
We can do the same thing using a 22.4% (MMS) stock solution. With a 22.4% stock solution you would add 2.7 ml to the gallon of water.
Both ways work out to the same concentration in the working solution but it is much easier to measure 12 ml than it is to measure 2.7 ml. Any slight mismeasurement with the 5% stock solution has little impact on the final working solution. On the other hand a slight mismeasurement with the 22.4% stock solution can make a significant difference in the working solution. I prefer to keep things simple.
If your day starts at something like 7a and goes through something like 10p, you would need to drink 1 liter of the working solution during the period of time.