i dont believe in periodisation, but thats a side issue
Also, you would never see me consult a notebook in the gym! I see that quite rarely to be honest, mostly powerlifters.
I think most gym users get their routines from the gym mythology, word of mouth which is like a chinese whisper and gets mangled in the process.
And sometimes someone walks in who has read the latest routine from Flex, or online and tries to do some of it.
Some ideas are good, like squatting, but then with the lack of proper examples and advice it turns into quarter squat or something.
Very rarely you see an individual just walking to the strongest fucker in the gym and ask for advice. I have had that happen to me in sugden gym (shit gym) few times, respect to those guys.