That was the accepted method to free rings back in the 50’s and 60’s before commercial anti-seize products were available – worked too ! Redex and Plus Gas also worked, but yer Mum usually had a can of Esso Blue or pink [ name fade]in the shed that cost you nothing!
If you think adding paraffin to soak over night is weird, then you probably have not heard of the method used for freeing a seized piston to bore ?
Add the paraffin over night, and then set light to it the next day ! That also worked in 50% of cases.