I found a really good, simple exercise to help with sweep picking and it's starting to pay off for me. The theory behind it is simple: where do most people get in trouble when trying to increase sweep picking speed? The answer: when it's time to reverse direction. Especially when picking across 5 or even all 6 strings. When you're picking across in one direction, it's difficult to reverse while staying in time with the beat or metronome.
So this exercise directly addresses that problem: it involves two strings, lets pick the B and high E strings. And let's start on the 5th fret. Start by picking down on the 5th fret of the B string, then pick down on the 6th fret of the high E string. Then do the reverse by picking up on the 5th fret of the high E and then picking up on the 6th fret of the B string. You're basically doing a sweep pick across two strings, back and forth. Then do the 5th and 7th fret (using your first and ring finger), then the 5th and 8th using your pinky finger. Then go back, 5th and 7th fret, then 5th and 6th again. Of course do this to a metronome or drum beat and start really slow. Also, you should only do this exercise (or any sweep picking exercise) if you're muting is on point. Both in ascending and descending.
After doing this for a long while, slowly building up speed, you'll be amazed how much this helps you picking across all the strings.
I hope some of you can get some good use out of this! See you later