It depends very much on the type of work you are doing. If you are building a brick wall, then spreading out the hours isn't going to make much difference - it takes 100 hours to build that wall or whatever. Music practice is very different though as simple hours are probably not enough - you'd need to really engage with and commit the music to muscle memory (I'm no musician, just guessing).

Something like making a CRUD web app is probably closer to building a wall than perfectly playing a concerto. If you're trying to build in a brand new feature into your web app that requires genuine creativity and a difficult algorithm, then you'll probably find that creating that feature in a single intense session while still fresh is going to work far better than trying to patch it together across a day of interruptions.

The article doesn't say hard work doesn't work. But the study it describes shows that how and when that hard work is put in makes the difference between the elite and the "merely" successful.