6 months, during high school over the winter. Shower was broken (water would only come out perfectly hot or cold, nothing in between) and parents/landlord would not fix it. I kinda just gave up on it. Nothing bad came out of it. Nobody at home or at school ever said anything or even noticed, as far as I could tell. No, they were not just being polite. I watched everyone closely, as much as an experiment of personal curiosity as anything else, and there were no signs of disapproval, nobody had a clue. I suffered no social consequences whatsoever. Wearing a new set of clothes every day alone was sufficient to stay clean.
Can't decide whether I just have one of those Asian genes that make you not smell, or whether Americans as a culture are psychotically brainwashed by soap companies' propaganda to the point where even the idea of "spending more than 1 day away from shower" is worse than death for them. Never used deodorant either (other than to try it out - just makes me feel gross, sticky, and smelly). Imagine how much money those deodorant companies are missing out on me over a lifetime!