Does the sentinels universe have a continual continuity like Marvel or does it have periodic continuity resets like DC?
I think it might be the latter. Wraith's bio lists her age as 23, just a year after finishing college and adopting the Wraith persona. However, she's one of the longest running heroes, having first appeared in Mystery Comics #27.
Yeah, I was going to say, the last time I remember reading spiderman he was a 30-something school teacher instead of a struggling college kid (or teenager) like when he started out
Well, Marvel also has a floating timeline. Also, I think they've said that approximately 2 years real time passes for each year in the marvel universe.
On a slightly relevant note, doesn't the Marvel U run on a "10 years ago the Fantastic Four #1 happened and we update our characters history to reflect that", e.g. Reed Richards and Ben Grimm fought in World War II. Then Korea. Then Vietnam. And now Desert Storm.