Concentration is high on the training dwarves too, but I'm not sure where that comes from.
It gets used and goes up exactly like Student does. You could say it's a duplicate of Student as it has the exact same effects and is trained in the exact same way.
Thinking about this, it might be worthwhile to add [NATURAL_SKILL:STUDENT:5] to the dwarven raw, until Toady adds schools/daycares for children. If children can go to school and learn a trade, or go to military school and learn Student (not military skills), then they can become adults and start their masonry careers or go to boot camp with a skilled teacher who will quickly rank them up. If this is done, then children will actually have a value instead of a liability. Children of soldiers could also watch training, gaining some skill from Bring Your Daughter To Work Day.
Either way, very interesting results, but mostly useless because there's not a huge way to actually utilize the data. Getting a good student is good, but unlikely, and therefore training by demonstrations is difficult at best.
Knowing the results are useless is worth the time getting them. I'd say the main point is that demonstrations are good for training up the defensive skills which are much slower to learn in live combat compared to offensive skills. Indeed, rather than adding [NATURAL_SKILL:STUDENT:5] I think it'd be worth more to just remove the tags for punch, kick and bite so dwarves cannot dilute their training with useless martial arts skills (wrestling still is useful for dealing with charges).
Once schools are in to train children, forts that raise up lots of children (maybe with a lower age of adulthood) will have a powerful pool of dwarves who learn skills quickly. Best would be if you could tell dwarves to attend 'university' even when they're adults.
As i see it perfect longterm embark is weapon skill 5 and teacher 5. Teacher 5 and defence skill(s) take long time to train to good weapon skill so you will probably be forced to use those dwarves in combat (including first sieges) and they will gain bad skills since they will do most fighting.
In my current game i started with 6 dwarves with sword 5 teacher 5 and they trained recruits resonably well, i had ~15 legendaries in year 3. Then massive hard sieges happened and after everyone gained unarmed skills training became really slow.
You may have a point, but not because training weapon skill is slow. What you'd get is suppression of sparring since dwarves don't like to spar when there's a massive skill difference. Given drills also raise weapon skill, you've got a system for focussing all training on weapon skill through a marathon of demonstrations. It could work I guess if you leave defence to good armour.
The alternative in my view is to embark with Teacher 5 and Defence 5 (be that Dodge, Armour or Shield skill) dwarves. Let them do a bit of demonstrations to each other at the start and then equip them with training weapons and go kill some wildlife (hope you have Agile dwarves). A year of killing wildlife with training weapons can get you from Lv 0 to Lv 8-ish in weapon skill. Capture and strip ambushers and snatchers too for more live training. By the time the first siege comes, you'd have a small core group of legendary weapon skills who also have some key defence skill to teach when the demonstration subject happens to land on defence.
Problem with this plan is that you can't let migrants into this core squad as it'll dilute the training - you want the core dwarves to be training each other not newbies at first. It'll probably be many sieges before they're ready to teach any skill to any recruit. Therefore it's best to have migrants train as marksdwarves instead of melee. So you'd eventually have 30~70 marksdwarves and like 4~6 hardcore melee dwarves. Given there's no friendly fire, this could take down any siege. In the long term you can now train up more melee dwarves as your core soldiers have lots of teaching experience and can teach any melee combat skill.