Training & Nutrition - Mixing HIIT with Sweet spot training?

I am following reccomendations given to beginning cyclists to train mostly in my sweet spot, and log as much time as possible without overtraining. The benefit of SS training is described that it causes less distress with faster recovery, thus allowing more time training and more benefit.

I also have interest in increasing VO2max.

Is it possible to "mix" VO2max workouts with sweet spot workouts to good effect? Or should I focus on sweet spot for the majority of the first 2 months?

I am tempted to perform some high intensity intervals at either the beginning or end of a sweet spot ride, and get a "combo" workout, and am wondering if this will limit my progress.

Thanks.

An even better thing for beginning cyclists to concentrate on is Zone 2 riding. This is described as lower training threshold riding. One should be able to easily speak in complete sentences without pausing. A couple of months or so of that will do you more good than anything.