What do you mean by "3rd route?" The rush of larger mobs toward the end of the Entertainment District, or the area earlier with the different-colored hyenas?
Ah, ok. Yeah those are all about speed, prioritizing the right enemy, and maybe just a bit of save scumming. Don't just blindly attack: pay attention to where your multi-attacks land, and if one guy's about to go down, sometimes it's worth it to prioritize rushing him with a regular attack rather than waiting for your multi to recharge.