Poliquin doesn’t advocate just one split. He advocates different splits based on recovery rate, stress, and other factors.
option A- 3 day per week whole body workouts
This is for hardgainers or people with no time to train, about 20% popluation
option B-4 day per week Mon/Thur lower body Tues/Fri upper body
this is for people with time to train, and a decent rate of recovery…most recreational workout buffs about 60% population
option C-5 day revolving split
he uses many different variations, but the most popular is the day1 C/B day 2 Legs/abs day 3 rest day 4 arms day 5 rest
this constitutes about 20% of the population who have good rates of recovery, or who lead low stress lives and have plenty of time for supplementation, rest, and training.
Poliquin has stated that no split is any superior to any other. Everyone will respond differently to different splits and some splits will work for people better at different times in their training cycles or training age.