Just wanted to chime in on this old thread, in case someone else comes along with the same question (like I did a few months ago). I am a 47-year-old woman who has been using 5% minoxidil foam once a day for the past 3.5 years to combat diffuse, moderately thinning hair. I was pleased with the results I was getting; my hair had filled in nicely and hair loss was at a minimum. However, I was curious whether I could drop down to using it every other day to "maintain" my results. My experience was not good. After about 6 weeks of using the foam every other day, I noticed myself shedding a LOT more than usual. I immediately resumed daily use of the foam, but even now, weeks later, my hair continues to shed. I'm not panicked about it, as I am confident that it will grow back with consistent use of Minoxidil, but it is difficult to watch all that hair going to waste. :-(
In a nutshell, my personal experience (as a woman) is that daily use of 5% minoxidil is required to maintain results. I hope this information is useful to someone else.