It’s all folklore.
Plenty of folklore has been produced by piston aero engine manufacturers and others.
There are ways to find out if there’s ‘lead build up’ and fouled plugs due to the method of operation.
Fouling due to long taxi at idle is due to an overly-rich mixture. If it’s overly-rich at 1,000 RPM, it’s still overly-rich at 1,800 RPM. That is, unless you lean the mixture…
Aggressive leaning during ground ops and stop the fan as soon as you no longer need it. I remember one fouled plug in 35 years of flying pistons.
Last edited by Lead Balloon; 3rd Dec 2021 at 20:53.