I highly recommend not worrying about getting your knee down and instead work on a good body position and getting some good instruction. It's very easy to get into bad habits, making unknowing mistakes that can then cause problems when you pick up your speed.
Keith Code's California Superbike Schools are great and his books Twist of the Wrist are great too. I find his stuff very easy to digest.
FWIW, dragging your knee is not necessarily a sign of good riding or even fast riding. With poor technique, you can get your knee down much sooner than necessary. As far as using the knee to give you confidence while you ride, I've only found that valuable while on the race track with much higher cornering speeds.
I don't ever get that close to getting my knee down on the road. I like having something in reserve and it's just not necessary.
On the track, depending on the corner etc I might get it down earlier than full lean or get it down at absolute max lean. Some corners you want to keep the bike more upright to give yourself more traction to get better drive out of the corner, others you can deal with it leant over more.
That's a pic of me demoing the first one - knee was down in that corner later into the corner, but the bike can lean further. Leaning further in this particular corner means you sacrifice some traction (it's bumpy and also comes back onto itself), hence I'm trying to keep it as upright as possible. Body off and down to help do that. There's a couple of other corners on this track which allow you to lean the bike further, in which case I hang off a little less and even may pull my knee up - sliders aren't cheap, after all
.
Getting the knee down is not the be all and end all of being fast. Turn it faster and you can go through a corner at the same speed for less lean. Also, I could have had less style in that corner and been just as fast
.
