Well... that really depends. I used to be obsessive about it. Washing twice a week. Wipe downs and vacuums too. It was easier to maintain then let it get dirty in a sense. But that was before I had more adult responsibilities.
Now... I haven't hand washed my Tacoma yet. No auto washes that destory paint for this truck. Even if I'm going to drag it through the rocks and tight brush. That's different, lol.
But since it's been cold and lots of salt on the roads the past couple months, I was power washing it at least once a week. Especially the undercarriage. Like till I was convinced there was zero left. Even in the freezing cold. But one of my local washes has heated water, so it worked out.
But usually? Ah man. Hopefully once a month. Maybe twice.