1/2 hour lesson?

I am needing to change piano teachers. The teacher I was going to in her home was only charging $25 an hour but it wasn't a good fit. I just inquired at a new place and they charge 42.25 for 39 min. (169 per month for weekly half hour sessions.) but I wonder if a half hour is enough time. It didn't seem like I got a lot from the 1 hour that I was doing before but the teacher talked a lot about personal things. So my question is is a half hour lesson once a week enough for an adult beginner?