danger room makes training too easy, with a slight trade off of broken fingers.
and then current training mechanism is bugged, it's so hard to get dwarfs spar and training quickly, even with a great teacher with great skills.
Actually, its quite easy to get dwarves to spar. All it requires is to tweak the number required for training to take place.
If you have a 10 dwarf squad, and have it set to require 10 dwarves for training, then one dwarf decides he needs a nap, or food, or water, then
all TEN have to wait until they are all there and ready. Of course, as soon as that one returns someone else decides he's hungry ... and they never train.
However, if you drop the trianing requirement to four dwarves, then you can have six slacking off and still have four doing sparring or demonstrations. In fact, I once had four sparring, while the remaining six were paired off doing different demonstrations (dodging, wresting, and something else that I can't remember off hand) ... all because I reduced the training number from 10 to 4.
In my current fort, I set the minimum to 2. When I had just the militia commander, she did individual drill. As soon as the second member was drafted, sparring (wrestling) immediately commenced. As soon as I assigned them training spears and shields, they immediately started using them. Its been under six months, and one of my four military dwarves has already reached level 1 speardwarf from zero exp, another has level 1 shield user with the other three about to get it, and all of them having about 300xp in dodging/kicking/wrestling/biting/etc ... all from six months or less of sparring, no danger room, from zero xp in all military skills for all of them. (If only I'd gotten a military dwarf in one of my migrant waves
).