I just need to say something about “running gags”
Sherlock getting Lestrade’s name wrong is a running gag
If lots of characters got Lestrade’s name wrong, that would still just be a running gag
If an antagonist called him “Gavin” during a brightly-lit scene with banter and priest disguises and surprise naked people, that would still just be a running gag
If that antagonist lured him to a dimly-lit Battersea station, and she called him “Gordon” during an intense discussion of death and loyalty and heartbreak, that would be an abrupt tone shift but could still just be a running gag
But if he then said “The name’s Greg” and she replied seriously “No, it’s not”
And he responded with a visible quick intake of breath
And the death-and-heartbreak conversation turned into a serious debate about his first name, with a background of sad music
You’d start to think there was something pretty fucking weird going on