Hard reset aka 30-30-30. A 'must' before flashing firmware?

What do you think? I have not found it to be recommended in the English forum.

To do a 30-30-30 reset you must push the reset button with your router powered on. Hold it for 30 seconds with the router powered on. STILL holding it, pull the power cord for 30 seconds. Still holding it, plug the router back in and continue to hold the reset button for 30 more seconds. You will have held the button for a full 90 seconds without releasing it.