Age 51. In off season, 3 times per week with one two day break. I don't use heavy weights, but do 10 - 15 reps with little break between sets. I do a training method I got from track and cycling where I do 'super groups' of two to four exercises with opposing muscle groups and only have <30 seconds between sets. For example: Bench 10 - 15 reps, curls, seated row, triceps. This way you are giving the muscle group rest but continuing to workout. It has a mild cardio effect because your heart rate stays elevated during the group set.
I also do a lot of shoulder and core golf related work using resistance bands and pulley machines. I got the exercise's from Joey D's book , "Fix your body, fix your swing". I do these as the warm up for the weight training. I include legs as well.
During the season I will reduce to 2 days a week. As you get older, weight training becomes more important as we can lose muscle mass faster than cardio endurance. Also, every session ends with 10 - 15 minutes of stretching. My whole workout is 1 to 1.5 hours depending on the day.