There are still a lot of guys that follow Mentzer's style of HIT. He advocated 4-7 days rest between training sessions. Oh, and some of them even have office jobs.
I've made my best gains doing a 2 way split, training 3 days a week.
I've trained true hard gainers to work with weights as little as 2 days a week. Many true hard gainers see great results training this way.
If you are training with high intensity (heavy ass weight) there is no need to weight train more than 3 days a week. And if one tried they wouldn't be able to do it for very damn long.
HIT style training just isn't for everyone. But you can't knock the results it can produce.