EOD, so 3.5x/wk for me. It's a push/pull so it really couldn't get much simpler. I've done my share of body part splits as well as full body but this area in-between the two is where frequency,volume and intensity seem to come together for my particular temperament, check it out:
PUSH
Front Squat
Flat Bench
Behind neck press
Close grip press
PULL
Romanian Deadlift
BB Row (underhand grip)
Chinups (neutral grip)
Rear lateral raises
Concentration curl
The emphasis is firmly on moving my Front Squat, Romanian dead, Bench and BB Row numbers in the 3-8 rep range, the rest is purely volume so 5x10, 3x15 etc. , as long as the total volume that workout is around 50 reps each accessory exercise , it's getting hit almost (but not quite) twice a week so those reps add up.
It's working well
I personally find body part splits too easy to overcomplicate , over think and end up "majoring in the minors" - but then we're all different.
I'm turning 50 this year and frankly even "on" - more than 4 times a week would be counter productive unless either the intensity or the volume per workout was laughable.