They always argue on a Saturday, sometimes Sunday too. It's not too good as DS aged 10 has been known to copy what they say and worse (to me) the aggressive tone they use. DS aged 11 months sometimes gets upset at the same time and we don't know if it's linked. They also have a 14 month old DD who we never know where she is (we assume it's set around nap time as we never hear her).
The good thing about it being weekends is we're often out and if they start (it can go for anything from 5 minutes to 30 minutes, normally ends with one of them driving off and sometimes continues later) we can 'pop to the shops' and the DC don't know much about it.
They've just started which means DS1 will start thinking about it again (we've heard him telling DS2 not to worry Mummy and Daddy will never argue like that) and DS2 will hear it as he goes to sleep.
Arg!