How can I give my players shooting practice without making them wait in line?
Think about shooting this way: The shot is the final touch, but finishing begins immediately when your team goes on the attack - so train your players to finish. The shot on goal is the technical piece and finishing is the tactical piece of the game.
For example, split the team up in two groups. Play in an 18x18 yard grid with a goal on each endline. If you only have one goal, teams alternate going toward that goal.
The team with the ball must shoot as quickly as possible. When the defending team gains possession, it must go to goal as quickly as possible. The coach serves a neutral ball after every goal. Rotate the keepers on every goal.