This is actually something that has been bothering me for quite a while too. You often read it’s optimal to hit a muscle twice a week for optimal progress. On the other hand, many programs are set up in a way that would only train them once a week, like many 5/3/1 templates, many of CT’s programs, etc.
Personally, I feel better training them twice, especially when it comes to upper body. But for recovery reasons I only do each of the big lifts with heavy weights once a week. So it currently looks like this now:
Day 1: Bench intensity (= heavy), Overhead Press volume (= lighter, more volume), shoulder accessory
Day 2: Squat intensity, Speed Deadlifts (low volume; not a big fan of high volume DLs), deadlift accessory
Day 3: Overhead Press intensity, Bench volume, chest accessory
Day 4: Deadlift intensity, Squat volume (not too much due to recovery issues), leg accessory
I add some arm pump work on upper body days and ab work on lower body days.