Thermodynamic vs kinetic reaction control with radical substitution

Doing a revision for a chemistry class test tomorrow, I stumbled upon thermodynamic and kinetic reaction control in the context of radical substitution.

Here, my chemistry teacher said, that thermodynamic reaction control would basically be about favoring stabilized (originally instable) transition states, e.g. by increasing temperatures. According to him, this would "thermodynamically prefer" the substitution of tertiary hydrogen atoms relative to primary ones.

However, he also told us that kinetic reaction control would, instead, prefer the substitution of primary hydrogen atoms. More precisely, the fastest reaction (which would result in the substitution of primary hydrogen atoms due to less steric hindrance) would be favored under certain conditions.

The question is, under which conditions a certain type of reaction control would be prefered.