Bring a large pot of water to a boil. Salt lightly, add linguine and cook to the package al dente timing. Before draining, reserve 3/4 cup pasta water. Plan to have the skillet sauce ready as the pasta finishes.

Pat shrimp dry and season with the measured 1/4 teaspoon salt and pepper. Check for shell fragments. Keep the shrimp refrigerated until the pasta water is nearly boiling.

Heat oil and 1 tablespoon butter in the skillet over medium-high heat. Add shrimp in one layer, using two batches if the pan is crowded. Cook about 1–2 minutes per side, until the flesh is pearly and opaque throughout. Transfer to a clean plate promptly.

Lower heat to medium-low. Add garlic and optional pepper flakes for 30–45 seconds, just until fragrant. Add wine away from an open flame, or use broth. Simmer 2–3 minutes. Add lemon juice, zest and 1/4 cup reserved pasta water.

Add drained linguine and toss over medium-low heat for 1 minute. Remove from heat and toss in remaining butter until glossy. Add pasta water a tablespoon at a time if needed. Fold in cooked shrimp and parsley just to warm. Taste before adding more salt or lemon.