it's fine for a beginner. anything running will build fitness. and it's always good for a beginner to work on speed first. 6x800 is obviously better for 5k but that's something someone more experienced needs. someone with at least a year of training
12x200 with full recovery (or close to it) at around 1-mile race pace is a fine early-season workout. Great neuromuscular training without putting too much stress on the body. I would probably cut it to 8. If this is intended to be faster than 1-mile race pace, I think it starts getting into risk-not-worth-the-reward territory.
I agree. We also have no context of what other workouts he's doing or will be doing.
OP I believe the idea is to work on turnover. Focus on making sure your form is good and trying to stay at least somewhat relaxed. This is what Jack Daniels' site says about rep pace:
Rep Pace Variety: Pace reps and strides. Intensity: Reps are fast, but not necessarily "hard," because work bouts are relatively short and are followed by relatively long recovery bouts. Recoveries are to be long enough that each run feels no more difficult than the previous run, because the purpose of Reps is to improve speed and economy and you can not get faster (nor more economical) if you are not running relaxed. If it takes 3 minutes recovery between Rep 400s, then that is what is needed. Reducing rest time between individual work bouts does not make for a better workout, in fact it probably makes for a worse workout because the short rests could increase the stress and lead to poor economy. Think of Reps as similar to current 1500 or mile race pace. Purpose: To improve your speed and economy.
As for the rests, I would say 75-90s would likely be fine if you're looking for an idea of the time commitment but you need not worry about how long the 200 jogs take. Also be aware that if you haven't done much speed (or are old like me) you may be extra sore from this workout than usual. Again we have no context of what you've done or your goal so it's hard to give much more feedback.