A comprehensive study examining 15 years of options data reveals that Theta, a crucial metric for short option premium traders, isn't perfectly reliable on a daily basis. Short options positions averaged less profit than their Thetas predicted, particularly for calls. Short puts demonstrated higher reliability as moneymakers compared to short calls. Managing trades early (from 45 to 21 days) significantly improved results and reduced risk. The research underscores the importance of trading small and frequently, as daily option P&Ls tend to be more variable than Theta suggests.