When I grew up in running in the 1970s and 1980s, the emphasis was on Long Slow Distance plus occasional intervals and hills. Today, however, there is more emphasis on shorter but intense workouts, as often as twice a week. This leads us to the question, should I do intense workouts more often?
I think the answer to that question depends on your goals for running or walking. If you are primarily interested in racing, then you should follow modern recommends for relatively short but intense workouts a couple of times per week. These workouts should continue through ones taper to a race. At least, the intensity should exist although the distance or time of the workouts might be tapered.
However, if your primary interest in running or walking is because you enjoy it, or because you're concerned about your health, forget about intense workouts; such workouts increase the risk of injury. Run LSD and enjoy it. When I first started running in 1973, medical and sports doctors recommended 1/2 hour three times per week for physical health. I don't know what they recommend today, but doing more than 1/2 hour three times per week is fine, as long as you enjoy it.
So, going back to the question asked in the subject of this post, should you do stressful workouts? The answer is ... it depends on your goals. Do what is appropriate for your goals. Do what is appropriate for your body makeup and condition. Do what is appropriate for your age. But, what ever you do, do it because you enjoy it and because you really want to do it.