This works for me all day: when I put it on at 7 AM until I get home after 5 with no color fading or creasing. I also live in a hot/humid southern climate where most of my friend have creases in their shadows mine lasts all day. It's worked better than any other primer I have used.
I usually get 8-10 hrs (I usually take my makeup off within that time frame) but I have had longer wear. I've never used it and had my shadow fade or crease prior to me removing my makeup. I recently had about 15 hours of wear and my eye shadow was still perfect...although the rest of my makeup didn't fare as well lol.
It's the best I've tried. The only other one that has come close was the Kate-something "spackle."
I've worn it all day and woke up with my eyeshadow still in place the next morning.
IMO, elf primer is just a concealer in a weird color.
I've gotten multiple samples of this and every time it is just garbage for me. My shadows don't stay for even 3 hours without creasing. And I don't even have very oily eyelids. I prefer the NARS smudgeproof primer.