As Buddha is auspicious by its nature and it rules Wednesday, thus it is considered to be good day and all auspicious works can be done during it. The nature of it is "ordinary, mixed", thus all "ordinary" types of works are good at this weekday. In combination with "mixed" Nakshatras (Mishra or Sadharana Nakshatras which are Vishakha and Krttika) activity related to this Nakshatras will be very fruitful. As for effectiveness - Wednesday is effective during night and day both. Wednesday is auspiscious for everything related to green colour, works, related to intellect. All works that somehow are related to maintenance, finding solutions for any kind of problems, etc. are very auspiscious at this day (as Vishnu is a tutelary Devata of it). Adhi-Devata (superior deity who's ruling the day) of Wednesday is Hari (another form of Vishnu).
Works in following fields are prescribed for Wednesday: fine arts; all types of arts; literature-, music-, dancing & starting thereof; sculpturing; theatre; education; writing; learning of Vedas, Shastras; Moorti or Prateema (idol) making; Mantra Kriya; meritorious works; marriage; friendship; starting of fasting; taking of holy bath; trade; intellectual works, clever works; scientifical activity (science); metal work; war; argument; intelligence; ingenuity; messenger, diplomacy; physical exercise; collection of articles; juices and food grains; green sapphire; earth; clothes; fragrant articles; ending of fasting; works which take long time and works which finish in the middle.