Didn't really want to start a new thread since one already exists for this. I too have wondered how it works as worded.
Here's my take on it:
Normally, a maneuver is used to place an Aspect on a target which can then be free tagged once, and then Fate point invoked afterward. Someone who is affected can then use a Maneuver themselves to clear out that aspect ... so essentially, even with an extra shift of success to make it sticky, it still only lasts until someone clears it.
What I could envision with Evocation based maneuvers is this: Every additional shift (so above those shifts used for the maneuver roll, which is not necessarily 3) put into the spell not only makes it conventionally sticky, but also *renews* itself every additional exchange so that the Aspect can still be Invoked afterward (obviously, you only get one free tag on that Aspect). How's this as example:
GM: Troll sees you and charges you. *dice are rolled and Troll's swing doesn't break Wizard's magical block*
Player: Goddamn! I take step back and cast an Earth evocation maneuver to have the ground grasp his legs and give him the Aspect Earthbound! Let's say 4 shifts for the Maneuver and 2 for extra duration. *rolls against Troll's athletics and succeeds*. I use my free tag to Invoke this effect: He's stuck in place and can't attack me until he frees himself!
GM: Sure, why not! Troll uses a Might roll to break free ... uhm, yeah, do I even bother rolling? He breaks free and advances on you. That's his action.
Player: That Evocation is still active. I pay a Fate point to get the earth to grab him again! And my action, I toss the incredible fury of my fire blast at his face! Wooo! 8 successes! In your face!
GM: Troll rolls a 3 on his athletics roll, so 5 damage goes through. 2 is absorbed by his natural toughness, so it hits his 3rd stress box ... You hurt it's feelings. As his own action, he once again frees himself from your Earth spell. How are those Fate points there?
Player: Uhm, yeah, kinda ran out. So taking on this troll was a bad idea, huh?
GM: Well, maybe. Depends if you survive. Pick your next action wisely.
I think the only place where it could be different is on a grapple. I'd say in that case, even if magical, the Wizard has to concentrate and use his own action each turn to keep his opponent immobilized or else it would be way too overpowered.
I think this method might provide a good way to let player judge on whether they'd prefer to pour lots of shifts into what they hope is an unbreakable maneuver, or if they prefer to throw shifts at duration hoping to rely on their Fate point pool to keep control.
Thoughts?