I agree with everything you mentioned, but this. You will be surprised at the number of real world emergencies you get involved in. FWIW, when I was a candidate, I worked with one particularly terrible instructor. His students were grossly overweighted and many had little or no buoyancy control. Bad instructors for OW students can be great experience for DM candidates...
If you can get pool/confined water time take it. When you aren't working with students, you have a lot of time to work on your own skills. By the time you've mastered the horizontal hover, you'll find your air consumption to be much improved. Use your "free time" in the water wisely - if you are just watching and waiting, you can work on your own trim, buoyancy, kicks etc.
Lastly, remember being with students/divers is work. If you have to chase students because they've lost control of their buoyancy and they are plummeting to the briny deep as they attempt to inflate their BCDs by grabbing their snorkels, you aren't going to have the same air consumption as you when you're having a fun dive. Start every dive with a full tank. There's less stress, and you always need to have adequate air for contingencies (read about Rock Bottom Gas Planning). If you go in the water with 10 people, but only 9 show up at safety stop it sucks if you have to worry about running out of gas while you drop down to look for a little lost lamb.
You are also going to be in a position when you have to be able to self-rescue. If you are doing an ascent and develop a reverse squeeze, for example, you can't count on anyone else to have enough gas to hang out with you until you get to the surface. The same thing goes for accidental deco. If you are on dive 6 of the day, but your students are on dive 2 or 3 and you loose a lamb, descending to look for said lamb may put you into deco.