[wastedhours]

Was coming here to say exactly this - you're not really being paid for the work itself, but to have access to you for a certain amount of time. Sometimes there's as much value to the company in your 2 minute Slack response to a query at 17:58 on a Friday evening as there is for a 6 hour coding block.

Not saying it's valuable in a world sense, but for the objectives of the machine you're working in, it often is.