It's entirely dependent on the personality and drive of the character. To wit with my PCs:

Deminos the halfling retired when he married Merilee, a halfling slave he'd rescued a year before.

Peter the wizard in a single adventure fought off two succubi as well an a Minor Death and concluded, "I'm too old for this (#&! anymore."

Lexania (Barbarian/Planar Champion) went back to her tribe after two years of rather unique adventures across six planes.

After four years of being an assassin and spy, Tral Dolenor opened a brewery. "It's less work and a file ale doesn't stab back."

Olath Vlos (Drow Rogue 10/ Cleric 5) didn't so much retire from active life as retire from adventuring directly. He runs a city now.