With cloak of shadows and either a rapid firing or enemy piercing spell, JtP is pretty incredibly easy. I did a lot of them early on to help with monster unlocks(one shotting Urban Crawlers? Yeah, I can get behind that.)
I do agree that they take forever, and without Cloak of Shadows they can be reeeeaaallllllyyyy tedious. Enemies have incredible reaction times and longer ranges than the player, so if you drop into range of one of those tiny robots(hard to see against certain backgrounds), WHELP, starting over bud!
I'm not sure how you'd really improve upon it, though. I like the mission, but its one of those that as-is, it kind of needs a certain sort of play style or enchant setup to do without driving yourself up the wall in frustration. Maybe if the mission forced enemies to always have those little indicator lines(so you could accurately predict their location) it'd be better? With that you could up monster frequency a bit to keep things interesting, without worrying about the player getting ganged up on by a billion monsters off screen.