Would be weird for the longest serving monarch to be replaced by the shortest serving one.

Which raises a good question... who was the shortest serving British monarch?

Oh, of COURSE there's a Wiki for that...

https://en.m.wikipedia.org/wiki/List_of_British_monarchy_records

"The shortest-reigning monarch was Lady Jane Grey who ruled for 9 days from 6 July until 15 July 1553 (although she was only proclaimed queen by the Lords of the council on 10 July). Her husband Lord Guildford Dudley was her consort for the entire reign, making this the shortest tenure of the male consort of a female monarch. Note: Jane's reign is disputed.

The king with the shortest definitively known reign was Edgar the Ætheling who ruled for 2 months, 12 days in 1066 before submitting to William the Conqueror. Some records indicate that Sweyn Forkbeard reigned for only 40 days in 1013–4.[7]"

Queen Elizabeth II died 9/8/2022, so Charles has already been in 514 days. He's good...