I was wondering if you guys use the same methodology to determine your gamma scalping break-even points on a delta-neutral trade (ie "theta loan"). I take the implied volatility and divide by 16 for daily scalp point, 7 for weekly, and 3.5 for monthly. Those figures are the square root of 250, 52, and 12 respectively. So for example, if I'm long a straddle that I bought at a 50% vol, I would need a 3.1% daily move or a 7% weekly move or a 14% monthly move before I could make a profitable gamma scalp. Until then I'm just paying my theta loan. It's the flip-side If I'm short the straddle (or whatever short gamma spread). Ie; I would be profitable for the day, week, etc until those percentage move #'s were breached. We used to use this "shorthand" quite a bit and I was wondering if it commonly known/used by other options traders.