I used about 70 igrip studs in a Surly Nate tire on the back of my fat bike and they’re great. Installing was easy, I saw someone online suggest pre drilling holes but I didn’t find I needed to. It might make them go in a little straighter but your going to spend much more time drilling and it’s not necessary. I’m going to add more Studs eventually because there’s a little bit of slip when the tire is between studs but not much. I wanted to see how few studs I could get away with. I have 160 studs in the front tire and there’s no slippage. I put 2 studs in each heel of my cycling boots and it saved me from falling when I had to walk the bike across a frozen Off camber bank. I also put 4 studs is each boot of my 4 yr old and 7 year old’s. Just 2 in each heel and and 2 in the widest part of the sole and they can run on ice with no problem!
My only complaint it that the tool that they provide you with accepts a 4mm hex wrench but it’s much easier to use a drill. So I had to put a 4mm hex bit in the drill then the tool with a stud inserted but that gets pretty wobbly. An improvement would be if the tool was directly mounted like a drill bit in your drill.
Overall a great product at a much better price than many studs from bike specific sites or stores. I have fancy studs in the front tire that have special shaped heads but I have yet to notice a significant difference (though not really a scientific comparison)