My understanding is that training every day is good for hypertrophy and perhaps endurance, but that it is not the best way to gain strength. The underlying notion is that the more work you do, the more capacity for work you can do. And that recovery time is nonlinear to the amount of work done, so that more but less intense excercise leads to ablarger capacity for work. However, if you are double fast-twitch and you want to play to your strengths (pun intended), you are going for peak power, not average capacity for work over time. In that case you get stronger by doing things that require more strength. That is going to still require recovery time that will not typically allow work every day. In fact, for strength training, best practice is still to avoid getting out of breath on recovery days.

Hypertrophy is a different goal entirely, and always had more volume than strength or power workouts, this data simply takes that to the logical conclusion. Whether its bro-splits or lots of compound work. You want to maximize average volume over any interval you could pick.