"Pretty much the same principles as your basic stealth techniques. When you want to disappear, it's safer to use those techniques in a crowd than on your own. I got a few reactions from I assume other Meisters with Soul Perception when I decided to try it with only a few other people around. Much more noticeable on their 'radar' that someone just disappeared than in a cluster of people. Also, if you're going to go solo, turn on Soul Protect before you reach your destination for the same reason."

It made sense, of course. If you wanted to stay off the radar, mask your signal somehow.