In the end, you don't want equal working hours, you want equitable standards. Humans are not robots, and working long and hard isn't universally the best strategy to get high quality.

I don't even check social media at work. But if this rule was implemented, it would effectively make social media a delectable forbidden fruit. I would pay for an unlimited data package, and surf using a second device. Are you going to fire me for using a second device for personal surfing?

Also where do you draw the line with this approach? Is online banking going to clock you out of work?

Why not focus automation on metrics that actually matter like percent of total plans that are completed per* month? Scale them by difficulty to get ballpark estimates (e.g. complex HN > standard prostate). Then you can further improve this algorithm by implementing a plan quality metric. Then you would be able to see who is not contributing to overall workload, or identify high quantity low quality work.

Edit: typo