I recently changed the way I hold my pick(I used to use the softer part of my 1st finger now I use the side of the first finger). I did it because it allows me to angle the pick better to reach higher speeds when alternate picking. It still feels a little bit weird because I'm getting used to that. My alternate picking speed is just as fast as it was before the change but my sweeping speed has slowered drastically. It feels like I have just started to learn sweeping( the pick won't cut through the strings very easily).
Should I angle the pick while sweeping like I do now usually or should I hold the pick perpendicular to the strings(no angle).
Angle it. The idea is that you want just enough contact to get the string to vibrate, you don't need a lot. From what you described it sounds like you're developing technique is pretty similar to my current one. I've had a great deal of success with angled, but not too much. Just brush it over the string. Hoped this helped
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I angle my pick the same for sweeping as I do for alternate picking and I've not had any issues. One thing to check though is that you're keeping a nice, relaxed grip on the pick during sweeps.
Speed is a by-product of shut the fuck up.
So I guess I should also get rid of the habit of angling the pick towards the direction I am sweeping since the new way I angle my pick allows me sweep through the strings freely enough?