Back test them and observe for yourself. My observations is long straddles and long strangles as a systematic trade have negative expectancy. Short straddles and short strangles as a systematic trade have a slight positive expectancy. In my opinion, you need an additional edge to make the trades worthwhile. The tasty trade reports on this may interest you, however, you need to take them with a grain of salt, as they do not publish the actual details of their study (only some details are avail). For example, the magnitude of their findings may not be correct but the sign of the value seems correct (the decimal point should be in the correct place but the digits may vary a good bit).