Why 50/10
Fifty minutes is the length of a lecture, a therapy hour, and most meetings, which is not a coincidence: it is about as long as most people sustain directed attention on one thing before quality drops. DeskTime's 2014 analysis of its most productive users found an average of 52 minutes of work followed by 17 minutes of break, which is close enough that 50/10 is the practical version.
Use it for
Writing, coding, problem sets, and anything where the first ten minutes are spent loading context you do not want to lose to a five-minute break.
DeskTime (2014), analysis of app usage among the top 10% most productive users; widely reported as the "52/17 rule".