Here's how I do it:
1. During the Winter, when I play little tennis, I lift 3-4 days per week. I lift much heavier in the Winter. I do splits twice a week, and a whole body workout once or twice a week. I never come close to a max lift. I don't do much benching, though I have recently done 4 x 205 at the end of a 4 set benching routine. I SQUAT heavy twice per week in the winter. Do Goblet Squats one day per week, Winter and rest of year.
2. During Tennis Season I'm lifting twice per week. Both workouts are whole body workouts, though I keep changing the lifts. I rotate through about 20 different exercises.
I also run and cycle quite a bit all year long.
At my age, I need rest. I need balance, and I need flexibility. I also like to look as though I won't blow over in a strong wind.
Everyone is different. Find your own way, grasshopper!
What is the most important element of training? I think it's CONSISTENCY. Go to the gym, or get out for a run or bike ride. Do something. Do NOT sit on your butt thinking how tired you are, or lonely, or got a little cough, or your pinky hurts. LOL! I think I hear a new reason for not training once a week....
These are our bodies, the toy we were born with. USE IT!!
Just my humble opinion. I'm sure I'm wrong, as usual.
-Robert