I once worked somewhere as a contractor where developers had 3 separate PCs with a KVM switch - with there being separate development, test and production infrastructure.
Ironically they had a serious production incident that almost took the entire (large) company out for a day because they were doing load testing in one environment (they had about 10 separate environments) but they had shared email infrastructure between production and the production-1 environment. The application being tested generated zillions of emails using "real" email addresses that clogged up their production environment.
My worst: Developer machines were dumb (but secure) terminals for remote desktop connections to a jump box, where a VNC connection got us to a Linux desktop living on AWS GovCloud where actual development took place.
Ironically they had a serious production incident that almost took the entire (large) company out for a day because they were doing load testing in one environment (they had about 10 separate environments) but they had shared email infrastructure between production and the production-1 environment. The application being tested generated zillions of emails using "real" email addresses that clogged up their production environment.