[cwlb]

burnt trees are not good fuel. areas that have "burnt through" are lower fire risk. dead, unburnt trees are the problem.

[Trisell]

Dead burnt trees fall down and rot feeding the next fire that comes through that forest. Instead of logging those trees and using them leaving good trees and new growth behind.

[droopyEyelids]

Sounds like you're missing the concept of the fuel class of wood in a wildfire. https://www.fs.fed.us/rm/pubs/rmrs_gtr164/rmrs_gtr164_06_fue...

That explains some of it, but different types of fuel take different amounts of time to catch fire, so like a dry prairie can catch on fire about instantly, but live saplings of 1" will not burn unless the fire keeps going for an hour.

A decomposing log on the forest floor won't really burn till it has been in a fire for somewhere around 100 hours.