I was born in Liverpool, UK, and grew up there in the 1980s. The Scouse (Liverpool) accent is particularly difficult to understand, especially when local slang words are introduced e.g. “she’s fit laa, anyway let’s get some scram” (translation: “she is very good looking, anyhow, shall we go and eat?”)
To this end, and because I worked sometimes in nearby football rival city Manchester, I had to adapt my accent. I decided rather than pick up the Manc (Manchester) accent I would pronounce words correctly, but that does not mean not the King’s English.
“Yer” became “Yes”, regional slang was dropped or avoided (“ar kid” – Manchester slang for “my brother” and others avoided).
I was slated for being posh by friends, but I ended up securing a very well paid job out of university, for which I suspect during the interviewer (a room full of a Londoners) appreciated both my degree and pronunciation.
As an aside, my choice to drop the accent was vindicated when the (sad) Jamie Bulger case became world wide news, because the people interviewed had to have literal on screen translations for the strong accent, a fact I still remember to this day.