Please Note: I discovered an error in my explanation of this technique and have slightly modified the original post. Also, Christopher Schlegel has provided a link to the "Fretboard Learning" lessons belonging to his own (discontinued) Guitar Fundamentals course, one that is sadly no longer a part of the core curriculum. Find that link in his response to this post. TBH, that particular set of lessons didn't help me learn the fretboard any better than the current GF courses, but maybe what and how Chris teaches will click for you. If not, try this method. You have nothing to lose :)
Beginners hear it incessantly - gotta learn the fretboard, gotta learn the fretboard. Accomplishing that has become my white whale. Unfortunately, none of the Guitar Fundamentals courses taught by Lisa, Anders and Chris have been helpful to me in that one regard. So, I experimented with some alternative methods on my own and this one hit home for me.
By now I have the string names down pat - EADGBE, which allows me to immediately identify all the notes on the first fret. It's just the string names sharped (remembering that E sharped is F and B sharped is C). Knowing the string names means that I also know the 12th fret, which is an octave up and therefore identical to the string names: EADGBE. I also know that moving one fret up the neck (toward the body) sharps a note and moving one fret down the neck (toward the headstock) flats a note. Knowing that, it's easy to quickly identify all the notes on the 11th and 13th strings as well. Which means I already know all the open strings and the notes on 4 frets, without having memorized anything new.
Now just pick either the 3rd and 7th frets or the 5th and 9th frets, and memorize the notes on those 2 frets. Because there are 2 identically named strings on the guitar, you really only need to memorize a total of 10 notes to learn those 2 frets. Once memorized, you should be able to quickly identify all the notes on the adjacent frets (on either side of the 2 frets that you memorized) by simply sharping or flatting the memorized notes.
So, memorize just 10 notes on 2 frets and you will be able to quickly identify all the notes on 10 whole frets. That leaves just 3 frets (or 15 notes) to learn in whatever manner works best for you. After memorizing just 10 notes, my times for completing the Fretboard Trainer exercise (in the GT Toolbox) improved profoundly. I went from over 5 minutes to less than 60 seconds. 10 notes.
Ultimately, my goal (and yours) is to memorize all the notes on the fretboard unassisted (without the need for using "anchor" notes as navigational guides). Although the aforementioned method cannot (on it's own) achieve that goal, it does allow for very quick identification of individual notes that you will then have to memorize. In other words, this method eliminates the need for always having to start at the nut and count up the neck sequentially, note by note, until you reach your destination. It's a way to save a whole lot of time while completing the task of memorizing all the notes on the fretboard; nothing more and nothing less.
"Whatever you are, be a good one" - Abraham Lincoln