[tjohns]

One hour really isn't enough time. You can spend 30-40 minutes just getting in/out of busy terminal airspace, which would only leave 20-30 minutes for instruction - which is nothing. Most flight lessons are closer to 1.5 hours for a reason.

You're also legally required to maintain 30-45 minutes of emergency reserve, longer if you're flying IFR.

And again, this isn't even touching on the "long" cross-country flights that are legally required for training.