I've been using only revivogen, and only revivogen once a day for the past 8 months. I haven't noticed my hair get much worse, but certainly no better. I am a Norwood 2 about.
I did notice some tiny clear hairs, about 1 inch long, maybe 40-50 of them that I don't remember from before, but maybe they were longer before and are miniaturizing. Either way, I noticed those about a month after using revivogen and they are till there and haven't changed.
Last week I added folligen and lasercomb into the mix. My hair looks thicker already and some hairs started to grow really fast. I have maybe 40 normal hairs that have already grown down to my eyebrows, whereas the rest are only as long as my mid forehead. I'm going to keep using revivogen I think for another year at least, in combination with folligen and lasercomb. I want those clear hairs to thicken up.