The worst part of playing one course repeatedly is that you hone a set of skills for only that type of course. When you wind up playing courses outside your comfort zone, it gets difficult. For example, playing links courses demands an ability to hit lower shots because you are playing into winds. Playing the wide open and long courses demands distance far more than accuracy.
Additionally it stops challenging you in strategy because after 5 or 6 rounds of the same course, you will settle on a strategy that suits a hole and course and tend to stick to it
You are right about accuracy being the wrong focus. I point to making good ball contact as the best focus for a beginner. But speed sessions would be a more advanced training than would be helpful for a beginner. I believe in the "swing slow to make sure you hit it" school of thought rather than the "swing hard in case you hit it" thought that is common now.
Yes a softer ball helps a slow swing go farther, but many players struggle with a big 460 head. Sure that big face can be forgiving on off center hits but a low loft and slow swing speed guarantee bad drives. All other factors like shaft flex, kick point, angle of attack, spin, ball compression, etc... being the same, higher loft with low swing speed will give longer drives to a point. I have seen junior drivers with a 25 degree loft (about a 9 wood in my bag, also my 180 yard club) but most drivers are 8-12 degree. A 3 wood with 15 degree loft and a shorter shaft is easier to hit the center of the face giving a straighter and longer drive. With under 70 mph swing speed even a 7 wood will give more carry and total distance (given soft course conditions) than a 10 degree driver, and with shorter shaft should also be easier to hit consistent.