That is quite a phenomenal explanation. Just to reiterate one key part for your question, all of the energy systems (ATP hydrolysis, phosphocreatine hydrolysis

That is quite a phenomenal explanation. Just to reiterate one key part for your question, all of the energy systems (ATP hydrolysis, phosphocreatine hydrolysis, glucose fermentation and finally glucose & fat oxidation) can produce energy in tandem and/or independently in muscle and other cells. But, first listed higher power systems are depleted within minutes and require expense of other systems to "recharge" (supercapacitor analogy) vs. glucose & fat oxidation can pretty much carry on constantly but are much lower power due to slower speed/higher complexity of their pathways (rather than just a battery I'd say an analogy of renewable energy [glucose] + battery storage [lipids in adipose] is more suitable i.e. steady input of energy source = steady utilization/output of work that can carry on pretty much constantly). So, many systems can produce energy together/in tandem in the cells, but the higher power systems once exhausted can force your body to temporarily cease high intensity activity to rest and recover. Glucose and fat oxidation don't ever stop in that process, but in recovering those higher power systems your body prevents you from engaging in more high energy "burst" activities until those systems "recharge". Training can allow you to modify these higher power systems to last longer, and recover quicker, but there will always be a top end constraint where every person "runs out of gas" when performing continuous high intensity/exertion activity.