How many Sprints should I deliver during a school year?

There is no set rule for how many Sprints a teacher can or should deliver during a school year. However, I recommend no less than ten, so that students don’t become overly familiar with any individual drill. Consider keeping a list of all the Sprints you use during the school year. So long as they’re not repeated too frequently, giving the same Sprint at intermittent times throughout the year serves as an excellent review of previously learned concepts. Starting on the first day of school, make a list of every Sprint you deliver. Once the list reaches ten, start back at the beginning and continue rotating through the list whenever you’re not introducing a new Sprint into the rotation.

in his book, Make it Stick, The Science of Successful Learning, Peter Brown expounds on this idea:

 

Periodic practice arrests forgetting, strengthens retrieval routes and is essential for hanging onto the knowledge you want to gain.  When you space out practice at a task and get a little rusty between sessions, or you interleave the practice of two or more subjects, retrieval is harder and feels less productive, but the effort produces longer lasting learning and enables more versatile application of it in later settings.