I've been using 6 -8 drops mixed with minoxidil in a shot glass for 16 months now. I have regrowth on the side of my head, near round the temples point, some of the downy hair has turned terminal, hence why I continue to use it after this long.
Hard to capture on a camera. Also my thin patch looks alot better now days than a few years ago. For me HS has had an effect. Progress has been very slow, and it's not had a wow effect in terms of regrowth, but after 8 years fighting hairloss, hairs regrowing after the initial two year growth period from the big 3 is noteworthy.
Hair signals is worth the investment imo, but don't expect miracles, and use it as an addition to a strong regimen.
I've managed to keep using it this long because it's no real hassle just to add a few drops to my minoxidil, since i'm going to be using minoxidil anyway. Although if you are less lazy than me using after/or before minoxidil and applying seprately would be the best way to do it.
Also worth noting is that for a few weeks, and then 1/2 times a week I also use emu oil, which I love. Using emu oil after minoxidil or HS helps push it further in to the dermis, therefore increasing absorption of both liquids, while also acting as a great anti inflammatory full of vitamin E.
Peace and carrots