When you work in a restaurant, you might understand this common mistake. Working in a kitchen is a matter of being constantly in a rush. You need to run from one place to another, and make sure that the food is ready for your consumers. So, during this, you might want your commercial grill to start as fast as it can, to start with the cooking process and have the food ready to serve.
However, you need to give your machine a few minutes to heat up. If you decide not to do this, the food might not be as consistent as it needs to be. You can consider starting the commercial grill up a few minutes before the whole restaurant opens, so it will have the time it needs. In the long run, this will help you with the taste of your food.