It used to be you could only get up to 20x star fragments from wishes unless you had people visit your island, then you could get more, but I visited someone's island yesterday and I wished a number of times without keeping track. I don't know how many but I feel it was a little over 20x. There was no one else visiting and now I have picked up 23x fragments on my beach so far. Maybe I got credit for the few wishes they made, but I didn't think that was supposed to work unless you had visitors to your island.