I have no explanation in mind. Just have observed over the years that similar engines react differently to glow plug situations.

I even had one that even needed a touch of glow plugs when hot to restart. Yet the engine seemed solid in general otherwise.

Some four bangers show a real reluctance to start with even one plug out was another observation.

About the only rule I would apply. If I drove a diesel over time. Observing that it was always the same glow plug that failed. I would have that injector checked out for spray pattern etc.

Logically it is so easy to make a reamer it should be used with every glow plug change. Carbon can build up. Just the right size drill bit with some grease on it to catch some of the carbon can do it. Both cheap to do and takes little time top accomplish.