For my NLP Core week I personally do the 4x per week split. Back - M, Chest/Shoulders - T, Off or 20min cardio & Abs - W, Arms - TH, Legs - F. I just don't feel like I'm doing enough with 3 days, although during heavy travel weeks and such I will switch to the 3x split.
same schedule, but with the intensity movements/training style.
This means that my low back/legs have 5 days to recover from deads before squats. If I did squats Monday and deads on Friday, 5 days would never be enough time to recover from squats to get down into a deadlift position. When it's time to do squats again 2 weeks later I will have done my high-intensity leg work the preceeding Friday giving them 3 days until deads and you can recover much better from that. When training for size and strength I really like the day off between workouts for total body/nervous system recovery. I've tinkered with this for over a decade and this is what works best for me.
When I do my Core/ power week I don't even do any arm work except for the secondary work it gets during the bigger moves.
Mon-Legs/Calves(squats and SLDL's)
Wed-Chest
Fri-Back/Shoulders
then comes my 4 day split w/o major squats or heavy stuff but still very intense with rep speed controlled whihc allows the weights to be light but very very hard.
First of all, there is no way I can ever drag myself up to the gym to only hit abs and cardio..it's not worth the effort of putting the keys in the ignition to me..and I'll feel like I have trained everyday. I just knock everything out on my workout days.
As for the split, I think I'm going to the 4 day split since I will be doing alot of rack deads and my legs will not need the recovery time from traditional deadlifting.