I love these Tabata Bonus workouts; Cathe's two new workouts are extremely versatile!!!
Tabata is a type of HIIT; HIIT can be done approximataely 2-3 times per week; IIRC. Some folks say 20 minutes of HIIT is plenty per session, but some like to do a lot more.
I use the Tabata Bonus workouts as add-ons if I have extra energy at the end of my cardio workout. For example, today I did Horizontal Conditioning Volume 2, then Cathe's To The Max 30/20 HIIt, then still had a bit of energy and did the slide-n-glide Tabata. I almost did the Tabata Drills too, but thought that might be overkill, plus I was hungry.
You
can do too many Tabatas and suffer the effects of overtraining. Those two short 4:55 minute sessions, even both done together, shouldn't hurt you unless you've already done a lot that day.
HTH!