Then I'll start by twice a day and covering the whole area. I'll check the ml's though, to be sure I use the same amount everyday. Bought the liquid btw, foam seems easy but I have fairly long and voluminous curly hair: the foam would mostly get absorbed by the hairs and not the scalp I guess. A pipette with the liquid seems far more precise.
Why to check mls? You must mainly check, if you covered the whole scalp. Minoxidil is a safe stuff, so you don't have to be afraid of overdose. Except few hypochondriacs, even people on 15% minoxidil don't report more side effects than people on 5% minoxidil. At least the picture on internet forums suggests this. (Well, it is always heavily distorted, but in the negative direction. If they experienced side effects, you can be sure that they would flood this forum with hysterical posts.) The only side effects I observe on 5% minoxidil is more hair on the body - I must cut my eyebrows from time to time, and hair in my nose grows to the length of 2 cm. LOL