Not enough! I started way back in high school in the mid 90s, and through college I just noodled a lot. Then I fell out of the habit, had stuff all stored away. Recently my wife decided I should get wall hangers and to have my stuff out in sight/reach. And it really worked to get me to pick things up again. I read Fretboard Logic by Bill Edwards and I found that to be a fantastic way to open up my understanding of things. I started on Fretboard Theory by Desi Serna but it covers a lot of the same ground in a less efficient way so I haven’t finished it yet.