I put mine on with two gripples near my toes on the front as that's where I get a put a lot of weight while riding. I didn't use any on my rear foot pad with the cush low I think I'm pretty locked in back there. I might stick one more on the front or another on the back pad.
These are great so far though, love how much better my grip was on my first ride. Hopefully durability is good but they seem pretty darn stuck on for now.
The only downside to these is that they are kinda sharp for barefoot riding so I might not put them on my GT since I do some barefoot beach rides with that.