I'm awake about 17 hours a day. Of those I'm being productive maybe 10 hours a day.
My working definition of productive is in the direction of: "things that I expect I will be glad I did once I've done them"[1].
Things that I personally find productive include
- Chores
- Work
- Eating
- Cooking
- Reading a good book
- Watching TV with my Wife/Kids
- Playing with the kids
- Socialising with friends
But not
- Doomscrolling
- Watching TV alone
- Playing most computer games
- Sitting on the couch doing nothing
- Reading a book I'm not particularly interested in
etc.
If we could find a magic pill which allowed me to do productive things 17 hours a day instead of 10 without any side effects, that would be approximately equally as valuable as a commensurate increase in life expectancy. Yet the first seems much easier to solve than the second - we already have some drugs which get pretty close (caffeine, amphetamines).[2]
Now obviously the correct thing to do is both, but in the same way as we want a Manhattan project for anti-aging, we should also advocate for a Manhattan project for focusing/willpower.
I don't think that study shows much either way: too small and underpowered to show much of anything (aside from the attrition undermining internal validity).
Dynomight's primary criticism doesn't hold much water because it is (un-pre-registered) reverse p-hacking. If you check enough covariates, you'll find a failure of randomization to balance on some covariate, and you can, if you wish, tell a post hoc story about how that is actually responsible for the overall mean difference. Nevertheless, randomization works, because on average why would any particular covariate be the way in which the confounding is mediated?
Just have to wait for more studies.