Gloria Mark did a study in which she found that it takes 23 minutes to regain focus after an interruption.
[Mark 2008-04-06 - The cost of interrupted work: more speed and stress](zotero://select/items/1_LEFDRCCT)
Gloria Mark's book Attention Span:
https://www.amazon.com/Attention-Span-Finding-Fighting-Distraction-ebook/dp/B09XBJ29W9?sr=1-1
Podcast:
https://www.universityofcalifornia.edu/news/cant-pay-attention-youre-not-alone