There is an obvious hidden assumption that 20% rule results in a productivity decrease, which is true for coal mining or agricultural harvest work, but not so much for software development.
A bit less water cooler time talking about sports to avoid something boring, a bit less HN time, combined with fresh new perspectives and new techniques and new ideas can easily result in a net productivity gain. If as per other posts you do strict 40/wk then we all know that at 4:45pm most folks are stalling till 5 so if you officially let him whip out a book on cool new technology you've lost exactly nothing while gaining quite a bit for free. Only a madman or a fool would "start something big" 15 minutes before going home and you claim he's skilled so we can assume nothing of huge importance would be lost by whipping out a book at 4:45pm. Or on the other side of the clock we all know time is spent spinning up, some folks delete emails, some gossip or talk, if he spins up by reading "cool new tech book" or fooling around in another language for 15 minutes to get into the flow, again, you've lost nothing while gaining quite a bit.
Get there faster by going slower, kind of thing. If you're lost in the woods, running as fast as you can just makes you die tired, so slow down.
If it is just grunt manual labor like data entry, then it is probably too boring to be fixed under any circumstances, but you claim in other posts to never hire juniors etc so by your own definition you can't be that bad... probably.
A bit less water cooler time talking about sports to avoid something boring, a bit less HN time, combined with fresh new perspectives and new techniques and new ideas can easily result in a net productivity gain. If as per other posts you do strict 40/wk then we all know that at 4:45pm most folks are stalling till 5 so if you officially let him whip out a book on cool new technology you've lost exactly nothing while gaining quite a bit for free. Only a madman or a fool would "start something big" 15 minutes before going home and you claim he's skilled so we can assume nothing of huge importance would be lost by whipping out a book at 4:45pm. Or on the other side of the clock we all know time is spent spinning up, some folks delete emails, some gossip or talk, if he spins up by reading "cool new tech book" or fooling around in another language for 15 minutes to get into the flow, again, you've lost nothing while gaining quite a bit.
Get there faster by going slower, kind of thing. If you're lost in the woods, running as fast as you can just makes you die tired, so slow down.
If it is just grunt manual labor like data entry, then it is probably too boring to be fixed under any circumstances, but you claim in other posts to never hire juniors etc so by your own definition you can't be that bad... probably.