[JAS84]

Funny you should mention Doctor Who. I was looking at this just last night after going down a rabbit hole on Doctor Who title sequences. This YouTube video on the official BBC Studio's channel for Doctor Who from four years ago gives at least eighteen title sequences - not counting variants - that have been done over the last 60 years.

Yeah, they change when each new Doctor debuts, except for 2 (his first few serials still used the original OP, which wasn't out of date as it didn't show Hartnell's face) and 10 (no face in the titles, so only the credits changed, thus it counts as a variant and not a new OP). 2, 3, 4, 6, 10, and 11 all changed during their tenure as well. Of course that means they never last more than a few years.