I use the gizmo till both limbs have an even gap/bend the length of both limbs, maybe to a 15 inch draw length. It only takes 30 seconds to run it up and down both limbs. If holding a stick bow at any draw length for 30 seconds is going to harm it, maybe I should switch to making glass bows. Once both limbs have that even bend/gap, it's almost a sure thing they will stay even the rest of the way. For character bows with lumps and bumps, the gizmo is out. But the gizmo is a great tool and it will tell you where the limbs need wood removed. It's really no different than using a straight edge and marking the flat spots, it just marks them for you.
I like to make BBO bows, pretty much pre tapered cut and dried before they even hit the tree. I string them right up to a 5 inch brace height and use the gizmo to even out the limbs at that 5 inch brace height before even pulling it on the tree. Dean Torges advocates this in his DVD, Hunting the Bamboo Backed Osage. This BBO below was tillered at a 5 inch brace height with the gizmo. I have not worked it down the tree yet as I quit working on it last night when I got it to this point. But as you can see by the 5 inch braced picture, it has a very good start to being a sweet looking/shooting bow.
Anyway munkinstein, your bow looks nice for all the more experience you have. And the more you build, the better you will get. Absorb all the info you can here as there are many knowledgeable guys here willing to share their years of making bows. Just go slow and easy, looking for that nice even arc in the limbs while avoiding those nasty hinges. Once you hinge a bow limb, the damage has already been done and all you can do from there is try to even out the limbs and settle for a lighter weight bow. But the bright side is, you can always give the bow to a kid and put a smile on his or her face:)