It seems to me that in general if you aren't seeing the usefulness of evocation blocks, then you aren't making them strong enough. I remember the first game I played with a non-optimized character. I would throw up 5 or 6 shift blocks and they would immediately be battered down, especially the offensive blocks because they are opposed by any action. But now I know that they are much more effective when your character is capable of throwing 8 or 10 shifts regardless of whether they are block or armor.