Factorial experiments are more efficient than a series of single factor experiments and the efficiency grows as the number of factors increases.
fæktˈoːɹɪəl ɛkspˈɛɹɪmənts ɑːɹ mˈoːɹ ɪfˈɪʃənt ðˌænə sˈɪɹiz ʌv sˈɪŋɡəl fˈæktɚɹ ɛkspˈɛɹɪmənts ænd ðɪ ɪfˈɪʃənsi ɡɹˈoʊz æz ðə nˈʌmbɚɹ ʌv fˈæktɚz ˈɪŋkɹiːsᵻz.