Right, but it would be like the ISP knowing that you use Tor. Useful, but not that much if you do it constantly. This ultra-secure mode for example could send

Right, but it would be like the ISP knowing that you use Tor. Useful, but not that much if you do it constantly. This ultra-secure mode for example could send a 1 KB packet every 15 minutes, weather you are talking with someone or not. Something would also need to be done to incoming packets, so that they won't stand out. I'm sure there is a suitable protocol out there. This would increase latency and reduce capacity, but this is why it's called ultrasecure, some inconveniences are expected.