I believe in trying to make every putt at the right speed. My best drill is to practice rolling putts to an alignment stick lying on the ground. Start at 3 feet and move back in 2 feet increments, rolling putts getting them to touch the stick without rolling over the stick. In 15 minutes your speed control will improve. Over days and weeks you will have nothing but made putts and tap ins.
As you get better, continue to move farther back to 30, 40 feet and more. Even though extremely difficult at these distances, the focus on pure speed will have you close all of the time with the occasional made bomb.