Well, excessive runoff isn't good, it flushes the organic material out of your soil and too much moisture for too long can kill or damage the microherd and lead to root rot . . .
In my experience if you're getting even 1/2 gallon of runoff that's a little too much and you should probably water much much more slowly. Maybe 1/2 gallon or so every 15-20 minutes until you get a little runoff, just a few drips, then give it a little more.
Others may have differing opinions, but I used to do the same thing you're doing and now that I water much less and get less runoff I've had faster growth and happier plants.
I was always told about 10% runoff is ideal, so 1/2 gallon of runoff for 2-3 gallons of watering is too much, 1/2 gallon for 3 gallon is 16%, so that's a little high and you are flushing out beneficials as well.
Do you use chemical ferts or organic? I'm guessing you go organic in FF:OF as chem ferts would be counter-productive in that mix
