For those of you who use Dashing Diva, how long does it usually last?

I usually go to a salon, but this is the first time I've used this.

But after I applied them all, I was really surprised because some of them only lasted about two days.

I tried attaching a new design, and this one lasts for over a week.

So I looked it up and found out it's a matter of luck.

How long is it normally to go?