I’ve been practising it on and off as I’ve also picked up Symphony of Destruction’s solo to work on (with a completely different set of challenges!). I’m trying to experiment with getting the feel of the economy picking right. How it should feel like when going from one string to another in the ascending direction, working on consistency. It feels easier when descending, going towards the lower strings than when ascending, so I’ trying to see what I do right going up to try to apply it when going down. On the few examples we have of economy pickers, it does look effortless from afar but a lot of techniques, not only in guitar do look effortless but they aren’t always really effortless. When I asked Frank Gambale about it, he very obviously said no, both sides were equivalent in smoothness and that he was picking pretty hard. Sometimes I think it’d be way easier to brute force it with alternate picking!
There’s also that the rest of the song is pretty much alternate picking, somewhat cross-picking. You really have to switch gears from one motion to another. Like this section before the two solos that’s a good workout… if you try to alternate pick everything! As the tab may suggest, I doubt it’s alternate picked on the recording: some of the sections are globally in time but not exactly on the click, very legato.