I was fortunate enough to own a share in a Chipmunk for 5 years.
Normal procedure for us was to leave the brakes off for both take off and landings.
The only exception was for a take off with a significant crosswind from the starboard side. In this scenario, it is possible to "run out" of left rudder due to the combined effects of gyroscopic precession, propwash and crosswind all conspiring to turn the aircraft to the right (Gypsy Major runs the opposite way to Lycomings and Continentals).
The couple of notches of brake is so that the left brake is just binding at full left rudder deflection, helping to keep her straight.
Generally, correct and copious use of into-wind aileron was more effective than using the brakes.
WP.