If you want the perfect texture for anything from shrimp cocktail to shrimp scampi, I suggest a very simple trick that takes only 15-30 minutes, depending on the size of your shrimp.
For one pound of shrimp, use a quarter cup each of salt and sugar. Dissolve them both in a cup of very hot water. Add ice to cool the solution. Add the shrimp and top with cold water so the shrimp are submerged.
Allow to sit in the fridge for 15 to 20 minutes. Drain, pat dry, and then prepare your dish as usual.