I end up doing a char light about half the time, and when I do, it is because the tobacco seems to need to settle in the bowl. It burns and expands and is no longer packed. This doesn't relate to how hard it's packed in the first place, more about how it is cut and how dry it is
"There is even a brand of European smoking-tobacco that
I like. It is a brand used by the Italian peasants. It is loose
and dry and black, and looks like tea-grounds. When the fire is
applied it expands, and climbs up and towers above the pipe, and
presently tumbles off inside of one's vest. The tobacco itself
is cheap, but it raises the insurance. "
Mark Twain
Same with me, I char light if it needs it.