I doubt there is “data” in the publishable research sense but my guess would be that coaches and athletes do have views based on their experience. And that anecdata is still data 
I know for me, blocking long endurance days seems to be beneficial and seems to give good returns in just a few weeks. Obv there’s no counterfactual–there’s no doppleganger version of me that did something different during the same period to compare against–but it seems to work, at least in the “base” period where you are willing to accumulate and carry more fatigue.
What i often do in the base period is intense intervals on Friday (higher intensity than sweetspot; i don’t really view that as high intensity, more like tempo), followed by long day with tempo portions on Saturday, followed by long day with any tempo portions that i can manage on Sunday.
The first time in the year that I do this, i’m shelled for days and have to take a rest week afterwards (so I do it to end a block rather than at beginning).
The second time I do it, I can resume training probably on Tuesday, or maybe wednesday albeit not feeling great (e.g. wouldn’t schedule a important quality workout for that day)
the third and fourth time, I feel fine. And if i slept enough, Whoop and subjective feelings might even tell me i’m ready to rock on Monday morning . . .