My playing and hands have taken a real beating lately as I stated in another post from fatigue and I think a big part of it is trying to get those damn position shifts down smoothly!! I’m talking when you go from one box position to another box position linearly on the fretboard. Eric either slides into them or pulls off a note but they’re so hard to get down smooth and in time. I’m starting to get the fives mechanic just playing up and down in one box position great. I can do it comfortably from about 170 to 200 tops BMP. But when I try to play through various positions like the cliffs of Dover intro I get stumped, lost rhythmically, and my fretting hand gets sloppy. Playing with a metronome or playing those passages with music doesn’t ever seem to sound right either. I guess Eric wins again and it’s just another example of what a brilliant guitar player he is. Anybody else running into this specific problem and how did you fix it?
Sounds like you’re making progress on single position 5ves. That’s a good place to build on.
Have you tried improv while shifting only 1 position? It’s a smaller piece to chew on, than sliding over the whole neck!
After you can do that, try single position fives in all 5 positions + octave position.
Then connect each position, one at a time. Ascending the neck & Descending the neck.
Eventually your muscle memory gets familiar with all the patterns, and it’s easier to put the puzzle together.
Yeah improvising these sort of licks to backing tracks is one of the things I think helped me breakthrough to kind of understand what was finally going on. Just trying to do this with a metronome doesn’t really work for me in the sense because it doesn’t help with feel. I can play the EJ fives sweeping thing descending in all five positions at his speeds, possibly faster and it’s such a cool sound when you finally get it down. It was that tumbling down the stairs and landing on your feet triplet quality that was so hard to get down. Now connecting let’s say the 12th position to the 9th position in E Minor?? That’s where it starts getting tricky. Trying to get through even more like the one in the live version of Western Flyer? Forget it! It’s the notes in the shifts that never sound right, or in time for some reason. 
Guess I’ll keep plugging away until it does.
One thing that helped for me was initially abandoning the note for note application of the cascades. Particularly the Cliffs one as that one is extra awkward. What I did instead was try to make up my own cascade type licks using 3 or 4 positions. In doing that I realized one advantage of cascading across the multiple positions in pentatonic is that you can achieve certain combinations of notes that would otherwise be awkward in a single position. So, in E, I would come up with an awkward descending lick in the 12th fret box and see if I could simplify its playing by descending across positions. Not sure if this is helpful to you but just putting it out there. 
Yes that’s very helpful and I’m pretty much doing the same thing. My goal is just to be able to have the technique of doing 5’s and sweeping so I could use it in my own applications with my own music. If I got up on stage tomorrow and had to do a guitar solo based around that technique I think I could get by pretty well. It’s just going from one box position to the other smoothly that I don’t have yet. The funny thing is I don’t know if I’ll ever even really need to be able to do that. I’m a singer songwriter in Nashville who’s music is southern rock and country and I highly doubt the music I’m playing it’s going to really be that called for ever. 
I can tell you though it’s still fun as hell to blaze along like what Eric does in those intros to cliffs of Dover. 