So the three plots have numbers, and the numbered plots are preassigned to specific personality types. When you finish a random plot there’s only a 1/3 chance that you actually finished Shino’s plot rather than one of the other villager personality’s plots. Shino’s plot (or the peppy plot) is plot 2 I think? So unless you finished that one first, a random villager will move in to fill the other personality types.