Carter Slade: Why'd you do it? Why'd you make the deal?
Johnny Blaze: I was a kid.
Carter Slade: What'd you get in return?
Johnny Blaze: Heartache.
Grisselle: Have mercy.
Ghost Rider: Sorry. All out of mercy.
Johnny Blaze: I'm fine. I feel like my skull is on fire, but I'm good.
Answer: The movie doesn't show how long the effects of the Penance Stare last. I have Morbius #1, in which Ghost Rider uses his Penance Stare on Morbius, who recovers from it relatively quickly. I don't know definitively because I haven't read very many Ghost Rider comics, but the duration of the effects could vary depending on how much remorse the person already felt for their past sins, or how much their own super powers allow them to recover from it. From what I understand, the Penance Stare doesn't work on the Punisher, as he feels no remorse for the people he's killed. It also had no effect on Deadpool, as his greatest victim is himself and it actually caused Ghost Rider to revert to his human form when he tried it on Deadpool.
Phaneron ★