How often do you schedule ads, and why?

I just hit affiliate last week, and during a stream last night I realized my viewers were seeing ads way more often than I would have liked (truly just a setting I had not messed around with yet). I think it's insane to expect anyone to put up with an ad break more frequently than once every half hour, no matter how long or short the ad break is. Imagine my horror when I found out Twitch defaulted me to a break every 18 minutes.

So, affiliates and partners, how often do your viewers see ads? How much does the length of the ad blocks affect that decision?