Hi again Paul,
If your cylinder head was made for short reach plugs, Ted’s advice sounds reasonable. Try measuring the length of the threaded part in the head. If it is 1/2″, then it is made for short reach plugs.
However, an engine goes better if the electrodes protrude into the combustion chamber. You may safely use your long reach plugs in a head made for short reach plugs if there is room for them. To avoid the problems described by Ted, you may unscrew them once in a while to clean them and remove deposits in the threads before they become troublesome.
As always, there are different opinions and different solutions – Ted’s advice is surely very sound if you have a cylinder head made for short reach plugs.