Keeping shells on during cooking is also a popular and effective technique. Shells help lock in natural moisture and boost overall flavor, making the shrimp juicier and more delicious. The real priority for safety lies in proper cooking methods—shrimp are done when they turn firm, pearly white, and fully opaque rather than translucent. Always keep raw seafood separate from ready-to-eat foods to avoid any risk of cross-contamination, and store everything at the correct refrigerator temperatures.

In the end, your mother-in-law likely prepared the shrimp just fine without deveining. While removing the dark line is recommended for better presentation in some cases, it is not strictly required for safety. Proper refrigeration, clean handling, and thorough cooking remain far more important factors. But what hidden flavors or textures might you discover next time you leave that line intact?