During the DAT days way back, we didn't have DAWs to boost your gain if needed. Since that was the case back then, I used to run my levels HOT. They we're peaking at around -2 back then. It was easy to go over maximizing your levels
But since I went 24-Bit, in 2006, with an SD 722, I could reliably run my levels WAY more conservatively, and since DAWs were around then, I could make my recordings peak where I wanted them to, which was around -12 to -8 most of the time.
As someone already said, when recording these days with my m10, I start my levels around -12, that way I have headroom if the FOH raises the gain throughout the show. This is especially helpful if I'm at a festie and I'm recording for 16 hours that day straight. I also NEVER mess with my levels UNLESS its between songs, or I'm just matching levels. But I can honestly say my recordings have gotten much more consistent since switching to 24-Bit, because I can run my levels conservatively, and do all the normalizing in post. No more HOT DAT recordings. Now my recordings sound much more natural in 24-Bit, since I don't have to slam levels in 16-Bit