This piece if for those who choose to incorporate a bit of HIIT into their routine. Your points are well-taken. As I age, I better understand that there is no single best approach. Can I run with you for an hour? Nope, for a variety of reasons. Can I walk for 30 minutes briskly? Yes. I am an advocate of any movement or non-sedentary behavior. HIIT is no panacea, but for those who do it safely, it can provide some health benefits. I do it occasionally with IFit on my treadmill, and view the 15 second run as safe. Other forms of HIIT mught literally kill me! I will not say this is good or this is bad (the walkers point out the knee injuries of the runners, the runners point out the efficiency and mental and physical benefits of their activities), but rather I tend to meet people where they are (with safety in mind). And to present the evidenced-based research outcomes. Thank you for your insights, and happy running!