I think circuit training is a great way to improve effectively, not only in golf but every sport. Take a short break of 10 to 15 seconds between exercises and do the cycle at least two times in a row except for the warmup. Of course you can do more rounds if you want to and are not too tired. This time we will focus on technique and strength.
You do not need any golf balls and can do this at home.
5 min – Warmup: Loosen up your upper body, arms and legs. Do some stretches and swing multiple clubs or use a weighted club or weighted donut.
3 min – Swing Medicine: Take a medicine ball with both hands and get in your normal address position with your feet parallel. Swing the ball five times backwards and back to the middle with a strong body turn. Do not swing through. Move the ball just back to the middle. Then take a very short break and do the same swinging to the other side. Repeat until the time is up. If you do not have a medicine ball, you can also use a water bottle or container.
5 min – Make it Swoosh: Grip a six iron upside down right behind the clubhead. Get in your normal address position and make full swings with it. Your goal is to make a swooshing sound with your club.
3 min – Turn it Slow: Grip your driver upside down. Grip it in the middle of the shaft, so your arms are extended normally, but place the clubhead on your chest. Then take your address position and turn doing slow backswing and downswing.
Do the training circuit at least two times in a row.