If they stay inside mostly and don't become "stinky", then that may be enough.
I live in the South and when we have warm days, my baby loves to romp around all over the yard. Plus, he sleeps with us, so I have to keep him fresh. I can't stand a stinky dog in my bed.
I tend to bathe every week and a half and sometimes I can stretch it to two weeks, but that's pushing it. He goes to the grooomer and get professionally cleaned up and trimmed every 5-6 weeks!