i've only done a few, but they were on fair weather days and i'm able to get the frame into my garage in just a minute or so. i do get the temperature in the garage up to about 80f, and only graft about 20 larvae so it doesn't take too long. so far the grafts and the frame of brood have done just fine after putting them back in the hive. the only problem i've had so far was failing to see capped queen cells on the frames that i put into the cell builder, oops.