Yep, this is it. I have 12-14 character passwords that are all highly secure with numbers, capitals and shift characters, different for every site, that I can just type off the top of my head.
Just need a pattern or algorithm. I use pattern, date shift, keyboard slide(i.e. w=q, q=p), shift.
I've used this for the past 17 years and never needed a password manager.
The only time I have issues is with a very few sites that do not allow shift characters(!@#$%^&*()).