Overcooking shrimp can be easily done. A few extra minutes can turn perfectly cooked shrimp into tough to eat bites. The above shape of the shrimp helps tremendously when eyeing during the cooking process. I primarily roast them on a sheet pan with lots of extra virgin olive oil, salt & pepper in a 400 degree oven. They cook quite quickly. After a few minutes turn then with a tong or spatula. Cook a few minutes longer. Press your finger on one. It should be firm but still have some give. Also be looking for the above left shape. Then take out of the oven and get the shrimp off the hot baking sheet pronto as the heat from the pan can overcook them quite quickly. Put on a platter or in a bowl. Enjoy!