Every large corporation I have worked with in the last 10 years has monitored internet access. Some block as well as monitor. The either monitor and block via network proxies and/or via locally installed software. When done locally the logs from the software are sent to a central logging system for the software. What the corporations do with that information has varied. Some don't actively look at it unless an issue arises and some send managers regular reports detailing the internet usage of their direct reports.

There hasn't been a company of any size I've worked for in the last at least 25 years which didn't require signing an acceptable use agreement which includes notification that all activities may be monitored.