Just read the abstract but seems to make sense. Weed (in a low/moderate dose) is great every once and awhile if you're trying to brainstorm or think holistically about how something should work. Sometimes if you have to work on something really boring it allows you to see it in a new light and appreciate interesting the aspects of the task. But if you're actually trying to get work done, good luck remembering what loop iteration you're on!
Despite the above, personally I have a hard time justifying getting "high on the clock" as ethical even if it makes me more productive in some things. Though it feels like having a little puff on a wide-open, set-aside Friday afternoon isn't too much different than having a drink in that situation, something I'm occasionally guilty of. IDK. What do people here think?