So are short high intensity workouts as good as long more leisurely ones?

That is what a growing body of research seems to indicate. From Fox News:

Many health groups have drummed into our heads that we need to do 30 minutes or more of moderate intensity exercise five days a week, totaling at least 150 minutes. But according to the Physical Activity Guidelines published by the National Institutes of Health, 75 minutes a week of high intensity physical activity can significantly lower your risk of heart disease, stroke, hypertension, diabetes and depression. That’s only 15 minutes a day, five days a week. If going all out for 15 minutes doesn’t sound like your thing, you can get the same improvements by doing 10 short, 60-second intervals. According to researchers at McMaster University in Hamilton, Ontario, young men who did high-intensity interval training, or HIIT, which involved 30 seconds of all-out effort at 100 percent of their maximum heart rate, saw similar improvements in their leg muscles as those who did multiple, hour-long sessions of steady cycling, and spent 90 percent more time exercising. . . .