Your method may work well for your but I consider it an extra step that is unncessary.
My discipline presumes that I am riding in contact. So moving a rein to "signal" that it's time to "collect" would be superluous. I also ride mostly with one hand and while I could do some sort of "finger waggle" that would, also, be superfluous. If I'm to increase or decrease the level of collection I'll do that with the leg/seat first, then modify the hand.
I will disagee that "the goal with a walker is to ride on a loose rein while in form". A huge percentage of Walkers work poorly on a loose rein and very well in contact. Now I mean "classical" contact not "TWHBEA Celebration contact" (where everyone has forearms that rival those of Popeye the Sailor). The type of contact you use is less determined by breed or way of going than by discipline. If you're going to try some eventing or anything in the classical equitation line then you'll need to be riding with contact.
If you're going the Western route or hack out on trails then you won't.
I didn't intend to demean or debase your approach. It may well work quite effectively in some disciplines. In others it won't. IMO the more "classical" approach works accross the board and, while it requires a higher level of rider skill and effort, pays larger dividends.