I've already suggested ways: Free tags.
So you've got to build multiple aspects or multiple tags into your rituals. This would make your rituals incredibly complex.
Lets say the base complexity (based on my formula is) is 9 + (Aspect + duration)*Frequency.
1 power for 1 day, then would be complexity 17, but you'd only get 1 free use for the day.
More times/day would be +8 shifts/tag
Each aspect would have to have its own duration. So you could have 5 aspects, each with a duration of 1 week which you could tag once each. They'd still last 1 week so, if you use up all the tags, you'd have to spend the FP's on them(as long as you pay 4 shifts to make them sticky).
This ritual would have a complexity of 59. (3X5) for 5 aspects: 15 + (7X5) for 1 week duration for each aspect + base of 9 = 59
lowering the duration to 1 day would be a complexity of 49.
To make it cheaper, you could have
An after noon: +7
1 aspect last 1 day +8
1 aspect last 1 week + 9
Base complexity: 9
That would be 3 free fragile tags for a total of: 33 shifts of complexity.
I'm not sure if that seems too high/low or seems fair. Just a suggestion.
Edit: And just to add to the chorus of voices, I'd like to point out a significant fact in the game:
OW pg. 92
Classic Werewolves
Description: As for werewolves.
What We Know: A classic werewolf is a person
who uses magic to transform himself into a
wolf; the magic reshapes the human body to a
lupine body.
Unfortunately, classic werewolves have to
learn how to do everything in wolf-form—
they’re still a human mind in a wolf body and
lack lupine instincts and experience.
The game didn't give were-wolves -2 Ritual: transformation. They used Magic as a narrative justification for spending refresh on shape-shifting powers, with a refresh cost of -7!
So I find it hard to believe that, just because someone has Thaumaturgy, they can use it to take 7 refresh worth of powers for free that a Shapeshifting character (with the justification of being able to use magic to shapeshift) had to spend a boat-load of refresh on. And, to boot, the shapeshifter only gets that one trick while the thaumaturgist can do much, much more like create wards, landmines, divinations etc...
If you want to be a wizard who shape-shifts, then really, you should take shape shifting powers.