That segment is not about turning the wheel faster, it's about spawning fiona/behemoth, which signal the end of the spawns. Turning the wheel minorly will only spawn two enemies. Kill them, turn the wheel minorly, spawn two more. Kill them. Repeat until 2 specific segments where they spawn a bunch of enemies. The first is just a random mob of standard mooks. Spank them. The second is the behemoth/fiona fight.
Couple tips.
Good CC is hard to find in this game, and a lot of it comes with Solas's Rift Mage Spec. But you do have access to a few.
-Mana Surge. This may seem like a primarily defensive passive, but if you know when your barrier is going down, walk up to a group of enemies and freeze them. You can then shatter them with precision/impact combos, like lunge and slash, long shot and shield bash. This is extremely effective at all levels, but godlike this early in the game. It's also the only AoE freeze you have access to.
-Knockout Powder. Great, long lasting group cc. Impact abilities like lunge and slash and shield bash rupture sleeping enemies, eldrich abilities like energy barrage nightmare them.
-Dispel Gets rid of fiona's barrier much faster than you dinking away at it. Also patented glyph-be-gone. Dispel is highly underrated.
Save certain abilities. For instance I have lunge and slash disabled on Cassandra. This is because impact abilities are more useful in my hands, than the ai's, who will use them whenever like idiots.
Make sure certain tactics are preferred. Evade, Fade Step, Shield Wall, Block and Slash should all be preferred. Also put the reserve stamina lower than 50%. Enough to use important abilities like detonators, but low enough that the ai doesn't sit there twiddling their thumbs when they have half their mana bar left.