My impression, perhaps misguided, is that (paleo) hunter-gatherers walked a lot, might have chased an animal hunting every day (but would not generally get completely tired), and perhaps played some sports. Once in a while they might have fought each other, which I imagine would be full-intensity. But that would be far from a daily, or even weekly occurence.
Is this idea correct? How often should you give a workout 10 out of 10 in effort? And if not very often, can additional maximum intensity workouts be justified as helping reduce the negative consequences of a sedentary lifestyle?