I have livebearers, cories and cichlids mostly. I feed 1x per day for 5-6 days a week. I generally do not feed them on Thursday (my maintenance day for the tanks).
I feed what they eat at the surface in 3-5 minutes. If you see food reaching the bottom, that's too much. Mostly I feed what they eat in 1 min, wait until it is gone and add the same amount - less mess and less waste reaches the bottom. Remember, (most) fish will not eat uneatten food once it has been on the bottom for 2+ hours...