I snap the thread or cut it. For me it's a question of whether or not I've waxed my thread, if I have it's easy to snap. Whip finishing is generally a 3 whip finish on Trout flies, more whips on larger stuff. I use no head cement on drys and emergers, just wax and a 3 whip finish. The flies have held up very well over the years. I do head cement on all my wet flies, Salmon, Steelhead and saltwater stuff.
wcglass