Myself, once a week.
There's no correlation between your gambling frequency and the results you get.
I mostly bet on sports, sometime there's a week where an underdog win more than favorite, sometime there's a week with full of unpredictable results. It's random and depend on how lucky your predictions is.
This sound strange though because I don't see myself gambling only once per week. I bet mostly on football and every day there is always match but not that I bet everyday. But Friday, Saturday and Sundays are the real gambling days for me and I don't consider that gambling too much because I try to gamble within a limit. As long as I have my budget for gambling, which I ensure I don't exceed, even though I see good matches every other days of the week, I will place my bet without fear.