OK, so here is my dilemma.
I've had Evernote Premium for around 16 years. I've worked in IT all that time and used Evernote as my own personal Knowledge Base. I, in my ever loving wisdom set up Evernote using only two Notebooks, one called Personal, and one called Work, I never created any other Notebooks after that, or used stacking. The way that I organized everything was by using Tags.
For Example I created a tag named "Work", which is tied to the Work Notebook, then I would create a sub tag name things like Microsoft, then under Microsoft I would create more sub tags undernea