Every other day. I always give my body at least one day to recover between any workout. I only do one body part every 10 days sometimes. I know it sounds weird but when I started I weighed 135lbs at 6', that was 4 years ago. For the first 3 years I trained 1 body part per week mon-fri and topped out at 170lbs this time last year. Then I started the EOD and sometimes every 2 days routine and right now I weigh in at 220lbs and I only went up 2% bf from last year.
So when I did the 5 day routine I gained about 35lbs in 3 years but my diet was shit the first year.
But when I switched to less training days per week I gained about 50 pounds in one year. Around 40 of it was muscle.
I've only met about 2 other people that do this type of split and are huge. For me less=more.
Just goes to show different strokes for different fokes.