It's the magic number theory. Unfortunately, there is no standard "magic number". For most shops, it's true that the more you have listed, the better your views and sales will be. Think about it. You'll have more variety, more chances of being seen, more tags to use, more eye-catching photos, etc. So as long as you have good photos, good tags, good titles, and good marketing and promotion, yes, 100 listings can help your shop, but really it's just a goal, it's not magic. It won't make you suddenly have a successful business or even a busy business. That part is so much more than just how many items you have!