If you insist on going to the range to practice, then really practice golf. Golf is not 50 shots with a 7-iron at a single target -- nor is that good practice.
Jack Nicklaus knows how to practice. I watched him at the Canadian Open in 1975 after his round. He got a bag of about 25 balls. He picked out a target and then worked over that shot like it was the most important one of his life. He checked the wind, his lie and the target distance. When he felt he had all the information correct, he chose a club, lined up and focused on delivering the ball to the chosen target. He hit the best shot he was capable of hitting.
Then he went down the line of professionals on the range hitting balls and talked to Arnold Palmer for a couple of minutes. He came back to his spot, picked out another target and went through the same process as if this was the shot of the century. After that shot he went down the line and talked to Lee Trevino for a couple of minutes, then returned for another very important shot with a different club and a different target.
Nicklaus was actually practicing golf. He aimed at different targets, used different clubs and took about five minutes between shots. It's against the rules to play on the course between rounds, so Nicklaus was doing the next best thing. This is the best of "sterile" practice and is more than I can reasonably ask from my students.
Learn to "practice" by hitting no more than two shots per club, per target, per day. You may not hit all good practice shots, but you will be far better prepared to hit good shots during your round of golf. Practice making specific kinds of shots; draws, fades, high, low, low fades and high draws. You will actually be trying to make shots rather than simply trying to hit as many balls as possible in the allotted time.
When practicing, plan to end your session on a positive note