I use 15% at night, but I use the dropper as I can measure out exact amounts and deliver the stuff through my hair (which is not hard these days!!), I then spread it around a little with the tip of my finger.
I have only been on Xandrox 5% in the morning and 15% in the evening for around 3 months now, but I am seeing more movement 'upstairs' than I was on 5% plain minoxidil twice a day.
Stay hairy
Ty