One technique used in factorial designs is to minimize replication (possibly no replication with support of analytical trickery) and to combine groups when effects are found to be statistically (or practically) insignificant.
wˈʌn tɛknˈiːk jˈuːzd ɪn fæktˈoːɹɪəl dɪzˈaɪnz ɪz tə mˈɪnɪmˌaɪz ɹˌɛplɪkˈeɪʃən pˈɑːsᵻbli nˈoʊ ɹˌɛplɪkˈeɪʃən wɪð səpˈoːɹt ʌv ˌænɐlˈɪɾɪkəl tɹˈɪkɚɹi ænd tə kəmbˈaɪn ɡɹˈuːps wɛn ɪfˈɛkts ɑːɹ fˈaʊnd təbi stɐtˈɪstɪkli ɔːɹ pɹˈæktɪkli ˌɪnsɪɡnˈɪfɪkənt.