It depends on your activity level, and how long you leave it on for.

It's strong when it breaks down a bit, so the lace sticks to it well.

When I wore a fullcap, I used it on the nape. And I had the most success than anything else, if it can hold on the nape, it can hold anywhere.

As a rough guide, if I'm exercising during the week. I replace it once a week, but I wouldn't want to go over a week as I like to give my scalp a rest for a few hours. A big tip...use a glossy magazine instead of a mirror slide, then use bubble wrap. Bubble wrap is so good, that I've stocked up on rolls of it, and cut it up into A4 sizes.