As the DM, I had a creature use (successfully anyway) the first* Fear effect I've ever run. Additionally, another player suffered confusion (though it was only for 1 round, so they didn't have a noticeable issue with it.)
*(There have been others but the saves always passed.)
The player whose guy ran away was fairly frustrated by it and I fully understand the frustration; but I am not sure if there's any good way to do fear. I've seen the revised 3.5 options but I'm not sure just having -X penalties is interesting enough.
On the one hand, I fully understand losing agency and I've really thought through if there's any way to narrate it such that the player would *choose* to run away. On the other hand, this *is* the point of will-save abilities a lot of the time -> Crowd control the players.
The same player has been put to sleep before (a few times) but that has a means to escape it (such as shaking the player awake.)
I foresee using more Fear/Paralyze effects on occasion and while he was a good sport and is quite interested in Iron Will and maybe another feat to get around it; I still feel like this is one of those things that *someone* in the community has solved (and yet I can't find any StackExchange, Paizo, or AngryGM threads on the topic.)
TL,DR - Do your players get used to it? Do you simply allow them saves each turn so they at least *can* come back?
Well, for me fear effects have always been the BBEGs low
level tactic of choice to survive against a group of PCs when usually one of them can kill him in one or two rounds.
Players aren't used anymore to losing. Either you make them get used to it again… or you change the encounters. Or play Hackmaster. Watch Gamers ("I hide behind the mount of dead bard bodies!").
If it's always one specific character who's done in because of a will save... change tactics now and then and allow him to shine too.