@Samer: same concept, slight different legging on NDX. 3-5 days market exposure, enter thursday the week before the expiration week. Market makers tend to reduce IV on purpose the friday to compensate for weekend theta decay. The risk graph is a bit optmistic, market makers will eat a good part of the profit with their spreads. Only diago can work, far otm and itm long calls on weekly have nasty spreads, so the trick is to use next month were the spreads are not too wide on far otm and itm calls (or puts).
This works best with NDX : has best IV/HV historically on all liquid indexes VIX excluded, SPXPM can be used too for the strategy. All other vehicles should be ignored even RUT (more contracts to pay for, market makers a bit more annoying with fills than in NDX) or AAPL (a stock can move widely on unexpected events, american) or SPY (here you have to pay many contracts and american) or ES option futures (overnight rogue prints, american).