First of all, you need to administer your AI according to its half-life. Otherwise, optimal dosing becomes less relevant when you allow uninhibited estrogen conversion to take place 75% of the time. The entire point of taking an AI is to maintain a normal degree of aromitization, but that isn't going to happen when there is no AI present the majority of the time.
Aromasin only maintains activity for about half of a day, so it is best dosed 2x daily, every 12 hours. By taking it EOD, as you suggest here, you are allowing aromatization to occur unhindered 75% of your cycle. This would be similar to someone asking how much D-bol they should take, yet the individual is only administering it once every other day. If you don't want to administer the aromasin on the proper schedule, then select another AI which requires a less frequent dosing scheme, such as Anastrozole or Letrozole. I prefer Aromasin for a variety of reasons, but most importantly because it does not negatively affect one's lipid profile, as do all other AI's.
As for dosage, 25 mg daily is generally sufficient for eliminating gyno symtoms in those who have allowed their estrogen levels to get out of control. Take 12.5 mg in the AM and another 12.5 mg in the PM. If symptoms are bad, then 50 mg daily may be best...again, in 2 evenly divided dosages. Regardless, nolva is always the best cure for stopping gyno in its tracks, while something like Aromasin is typically best employed for maintaining normal estrogen levels. This is because Nolva immediately stops gyno symptoms from worsening by displacing estrogen from receptors sites, whereas AI's do not. AI's simply stop the body from producing further estrogen...they do nothing to combat estrogen which has already been produced and is wreaking havoc on your titties.