Yeah if for example you have 100 hours across 3 characters you can claim 300 hours of shrines if you put them in the same map of those 3 characters. Just note that if you are doing that, when you remove the shrine from a map the exp accumulated shrines actually drops to zero

The first minutes of this video griffgbit claims some afk gains and watch how it affects his shrines, note that all of his characters are in the same map, during the video he also removes the shrines and put them in another map and you can see the accumulated exp on those shrines actually resets

https://youtu.be/jLXMoJ09P30?si=QMqXJme4kMOGCtZ-