since you didn't have a lot of extra water in that cooler, your ice usage was just more efficient.
I would wait until the gravity bottoms out and you know its 'done'. At that point you could def. stop adding ice and let it warm up to about 70F. rack to secondary or do a long primary...either way give the yeast enough time at 70~ to clean up any possible off flavors like diacetyl and other by-products.
Primary: English Mild
On tap: Pale Ale, Lancelot's Wheat, English Brown Ale, Steam Beer, HoovNuts IPA
Bottled: MOAM, Braggot, Raspberry Melomel, Merlot, Apfelwein, Pyment, Sweet mead, Cabernet
Gal in 2009: 27, Gal in 2010: 34, Gal in 2011: 13, Gal in 2012: 10