Complex sentence: As their number of clients increased, Varney sometimes did upwards of 25 different versions of a spot in a single day, due to his photographic memory... he would read through the script one time then insert the various products names on different takes.
Split into simpler sentences: As their number of clients increased, Varney sometimes did upwards of 25 different versions of a spot in a single day. He would read through the script one time then insert the various products names on different takes.