I thought the permanent special npcs and temporary npcs rotate.

[ctar17]

So Celeste only appears when there's a meteor shower/shooting stars of some sort (this constitutes certain types of "Fine" weather). There are two types of meteor showers and only the big ones will be announced by Isabelle and talked about by villagers. The smaller ones will have significantly less stars, and won't get announced or mentioned, but Celeste can still appear (maximum of 1 time a week though, if you have multiple meteor showers in a week, then it will randomly choose one of those days for her to appear).

 

[Imbri]

I haven't seen Redd on my island for a couple of weeks. Friends have had him, and I've bought fake art to put in my house or around the island. Once I've found a real piece to donate, if I get a 2nd real one, I'll swap it out. Most anyway. I think I'll keep the haunted antique statue around, and placed outside, it's hard to tell the fake beautiful statue.

 

[Red Cat]

Not from what I remember unless they changed it with the Welcome Amiibo update. I remember going months without seeing him and then seeing him back to back every other day sometimes. He seemed really random in New LEaf.

I don't remember if it was this way before the WA update, but once Gracie and Katrina were out of the picture with their permanent shops, Redd would show up every week along with Saharah, Gulliver, Joan, and Pete twice with one day left open or taken up by an event or holiday. NH added CJ and Flick and took Leif, Kicks, Label, and K.K. out of main street which results in a much more crowded special visitor rotation.

 

[meggiewes]

I don't remember if it was this way before the WA update, but once Gracie and Katrina were out of the picture with their permanent shops, Redd would show up every week along with Saharah, Gulliver, Joan, and Pete twice with one day left open or taken up by an event or holiday. NH added CJ and Flick and took Leif, Kicks, Label, and K.K. out of main street which results in a much more crowded special visitor rotation.

Ah! Maybe that is why he feels like he shows up a lot in NL. I only have him and Katrina visiting in Stardust.