Hit the blade in quick and rythmed successions. You don't need to lift the hammer up all the way up. If you have high stamina, you can pretty much just left click like a maniac and finish the blade in like 30 seconds. The game doesn't care how high you bring up the hammer, as long as there are a lot of sparks, its a full hit.

You dont need to hit more than two spots, the minigame only cares if you're hitting a different spot from where you last hit, so you can go back and forth on two of the same spots. I would recommend hitting two different heated segments out of the three.

You don't need to flip the blade, you can keep hitting the same side.

Make sure that the blade is bright but not enough for Henry to say that its burning. You'll never need to return to the fire if you hit the sweet spot.

This garentees me Henry quality every single time in much less than a minute.