Hi ratty,
For whatever its worth, here's my experience...
About 3 or so years ago, I experimented with am/pm split, Mon/Wed/Fri, for a full 2 cycles of HST.
So I had about 36hrs between Mon pm, and Wed am, and again Wed pm, and Fri am...
Yeah it seemed to be going well. My muscles got 'fuller' and harder, and maybe slightly bigger - though I probably wasnt eating enough calories at the time?
I also got leaner bf.
The workouts were hard going towards the end - enthusiasm wears off after a few weeks!
I was also lucky in having access to a gym at work, where I could train immediately before, and after.
I stuck with about 5 compound exercises - alternating things like squats am, leg curls/extensions pm (I just couldnt squat 6 X week!)
Also, I alternated incline bench in am, and dips in pm.
Rows am, chin ups in pm
Shoulder press in am, and lateral raises in pm.
I also alternated bicep curls am, and tricep extensions pm.
Just basics. The usual HST format of 1set 15s, 2 sets 10s, & 3 sets 5s and negs.
Hit failure on the last Fri of each 2wk cycle - both am and pm workouts!
Yes. I think I made noticeable gains. Maybe because it was something different to the usual 3X week I've been doing for the last 20yrs. Maybe because of other factors?
I would love to have the time - and energy - to do it again. I do think I made my best recent progress on this split.... but it is very hard going (especially as we get older) and time consming - dependant on work and family.
I kept my workouts to less than 30mins each, but including showering (twice!) and warm ups and cool downs/stretching off (very important both sessions) this is still a lot of time out of my daily routine.
I did briefly - as per Vicious's ebook - try am/pm split 6X week... but only managed two weeks worth.
Took up too much time. And was a shed load of serious eating!
I could also see that getting a bit boring, and once you start to get bored, you lose focus and dont make the progress you want.
So try the M/W/F am/pm split. Eat lots.
To be honest, if your working that hard, do you need to do cardio too?
I would suggest no more than 15mins after each pm workout - and dont just cardio your legs. Hit the heavy bag, or row too?
Hope this helps?
Good luck
Brix