You can easily grow on a caloric surplus with less harmful and less androgenic steroids. Why expose your body to a harsh substance when you can achieve the same goal off a different and more mild anabolic steroid. You'll hold water either way, you might look a bit more dry but nothing substantial. You would feel way better running a nandrolone like Deca or NPP instead of tren. It can substantially aid you during your off season and ease the poundages your joints receive each day. And you get just as strong. Also when it comes to orals, they all trash your appetite. It depends on the dose, individual and type of steroid. Some more harsh than others will cause a more noticeable suppression in your appetite. And when it comes to tren, some people notice a dramatic increase in appetite. Whereas others will experience the opposite. So the simple answer to your question is because it's better to save the harsh but useful steroid when it is the most needed which is during a cut and when calories are greatly restricted. It will give you that edge that you are looking for. Hope this helps, good luck