I don’t know if we are allowed to copy and paste from manufacturer’s manuals, so Moderators please edit if necessary:
From Airbus FCTM (A320) SOPs/ Landing/ Deceleration:
REVERSE THRUST EFFICIENCY
Thrust reversers are more efficient at high speeds: The flight crew must select reverse thrust immediately after main landing gear touchdown.
Below 70 kt, thrust reversers efficiency rapidly decreases. Below 60 kt with REV MAXselected, engine stall may occur. Therefore, it is recommended to reduce the reverse thrust to REV IDLE at 70 kt, and keep REV IDLE until taxi speed.
However in an emergency case, the flight crew must keep REV MAX until full-stop of the aircraft.
At taxi speed, and not above, stow the thrust reversers before leaving the runway, in order to avoid foreign object ingestion.