I think this is mostly a US thing. Why use yearly salary? You’re not paid once a year, are you? Most likely once a month. Referencing monthly salary makes much more sense.
“I’m making 50k”. Great, now I have to guess - dollars? Monthly? Yearly? If yearly then what’s the monthly paycheck? Net? Gross?
Two weeks (or weekly) is very common for people on hourly wages in most countries. Particularly those with overtime rules. It gets a bit confusing if you have a bi monthly pay and say overtime rate for any hours over 40 hour weeks. Your checks land on 14 to 15.5 days per monthly but your overtime may need to be calculated based on hours of a previous pay period.