This versatile dish is equally delicious served piping hot or at room temperature.
Finely grate zest of 3 lemons. Juice all 4 lemons; strain juice, and set aside. Place shrimp in a large bowl; add lemon zest, garlic, and 1/4 cup olive oil; toss well to coat evenly. Season with salt and pepper.
Heat a large saute pan over medium heat. Add 1 tablespoon olive oil, and heat until oil is hot but not smoking. Working in batches, arrange a single layer of shrimp in pan, being careful not to overcrowd pan. Cook until underside is golden brown, 45 to 60 seconds. Turn over, and continue cooking until other side is golden brown and shrimp is cooked through, about 1 minute. Transfer to a large serving platter. Deglaze pan with 1 1/2 tablespoons reserved lemon juice, stirring up any browned bits with a wooden spoon, and pour pan sauce over shrimp. Cover loosely with foil while repeating process with remaining batches, adding 1 tablespoon oil each time.