Question for relatively long hair NW2-3s on Rogaine Foam

[mmmcoffee]

Ive noticed that a lot of us on here are NW2-3s and are mostly scared about what the future holds in terms of NW patterns. So for those of you on rogaine and havent gone the buzzcut route yet, how do you tell if youve used enough rogaine foam?

I keep my hair relatively long for a guy, usually 2 months in between haircuts as im still at the phase where it looks thicker when its longer and it covers up my receding hairline somewhat. I put 4-5 "stripes" of rogaine all over the top of my head from hairline to crown and massage it in with my finger tips, but sometimes i feel as it mostly gets soaked up by my hair and doesnt reach the scalp, so im curious how do you guys tell youve properly applied it to your scalp