I understand. No aircraft need wait on the runway- pre-takeoff checks can be rapidly completed. The only reason there is a pause before take-off is to wait for a preceding aeroplane to take-off and get clear, or one to land and clear before brakes release. Powering up on brakes is not desired or recommended, though an intermediate power may be required in icing conditions to ensure the engine de-icing can work long enough to ensure there are no problems during high power for take-off. So the ideal is to turn onto the runway and keep it rolling while you spool up the engines, without touching the brakes.