The phrase "for the sake of this exercise" means to do something for a specific purpose or goal, even if it may not be practical or efficient in other situations. Full definition
Not like they are doing spectacular but just for the sake of exercise. (justarsenal.com)
For the sake of this exercise, we will pretend there is a sharp bettor who wins more than 55 % of their bets over a prolonged period of time. (sportsinsights.com)
With that in mind, and for the sake of this exercise, we're going to view Pjanic simply as a playmaker, one who is increasingly becoming adept in the attacking phases of the game, namely shot selection and, of course, goal scoring. (chiesaditotti.com)