On reddit I recently posted about my experiment where I got a Dwarf up to novice Engraving, and locked the novice engraver and a no engraver in an Engraver Guild Hall together. About a year later they were both legendary engravers simply from giving and attending demonstrations.
https://www.reddit.com/r/dwarffortress/comments/107tobt/in_a_new_fortress_i_locked_two_dwarves_in_an/The actual setup looked like this:
Though I feel it's excessively indulgent.
I then repeated the trick with two dwarves who I turned into legendary armorsmiths via an Armorsmith Guild Hall, in parallel I trained up a third dwarf to a Legendary armorsmith by making armor, and yeah, he trained up a good deal faster than the Guild of 2.
Then I took one of the legendary engravers, trained him up to novice planter, and paired him up with the spare legendary armorsmith (the one without a useful material preference) in a Planter Guild Hall to see if having high teacher/student would make a casually noticeable difference, they still got legendary Planter pretty fast, about a year, but if it was faster it wasn't casually noticeable.
I also then went to the effort to measure the precise time taken, in a new game I locked a novice engraver and a non-engraver in a Guild Hall together, I locked them in on 20th Obsidian, 126 and the first of them achieved Legendary on 3rd Slate, 128. By my calculations that is 13 and a half months, a slightly long year. I suspect the rate of experience gain is quite consistent since dwarves seem to constantly demonstrate, this is unlike military skill gain where dwarves randomly choose to do tasks that give little or much experience making the pace of skill gain over a year very erratic.
One may note the absurdity of taking a novice and a no-skill, locking them together in a room with almost no experience and no materials with which to improve their skills, and having them emerge legendary just from talking to each other, but apparently in Dwarf Fortress, "theorycrafting" is actually highly effective.
I have applied a small amount of thought to what to name this exploit, and "guild theorycrafting" is one option, another would be "guild bootstrapping", the important aspect here is the bootstrapping aspect, in that it's not a highly skilled dwarf uplifting others to their own skill level, but a pair of dwarves lifting their skill level without external assistance.
My working theoryFrom my casual observations of Guilds, it seems that having a high skilled instructor rapidly increases the experience of those attending the demonstrations, start with a Legendary Miner and a Miners Guild, and you'll quickly have dozens of Lengendary Miners.
The important question here, is how does starting with a Novice work? Where is the experience coming from?
My hypothesis is that when a Dwarf gives a demonstration, they also gain some experience. If this hypothesis is true, then a Guild of 2 would give the fastest "bootstrapping" experience gain, as each dwarf is giving demonstrations approximately 50% of the time, while if there were 10 dwarves, they'd only be giving demonstrations 10% of the time.
However alternatively, it might be that attending demonstrations awards some experience even if the instructor is not more highly experienced. In this case, "bootstrapping" would be faster with more dwarves.
Or it might be experience gains are about the same for giving and attending demonstrations, making it largely independent of the number of participants.
The experience gains from demonstrations could probably be easily determined with a third party utility which shows precise experience values, though I don't have them set up for the Steam version yet.
Practical utilityGoing from novice to legendary in about a year is reasonably fast, though given unlimited materials many skills can be trained faster.
But some skills are just plain slow to train or may have irritating "resource" requirements. For example to get to Legendary+0 for engraving would require engraving about 1800 tiles, while to get Planter to legendary requires planting about 500 seeds, both skills are very likely going to be trained up much faster using Guild theorycrafting.
Most skills require about 500 actions to reach legendary which involves a lot of materials and making a lot of "trash". In the case of the metalsmithing professions this can be melted back down at magma smelters, often for free or even profit, but for many professions it's either clutter or just has to be given to traders to take it away. Theorycrafting requires no resources and generates no trash.
On the lack of cruel and unusual methods.I know it seems remarkably humane to lock up two dwarves together with some booze and food and they just rub their heads together and become awesomely skilled while enjoying each other's company. Where are the hordes of peahens or dogs to nip at them and motivate them? Upright spikes? Goblins stripped naked and forced to fight? How can motivating them to learn be so simple?
Unfortunately locking two dwarves in a Guild Hall does really seem to be just this simple and effective, though I'm sure throwing in several dozen animals couldn't hurt.
On ChildrenIt is in fact possible for children to attend demonstrations and thus learn. So it was only natural to try locking a child in for mandatory demonstrations.
The results were somewhat surprising, children do attend demonstrations, but not only that, they can even lead demonstrations!
However from limited testing it seems children aren't nearly as motivated as adults are to attend demonstrations, preferring to instead socialize or even play (though they seem to play less when locked in a guild hall than they would if given free reign), thus the combination of adult:child would result in slower leveling than adult:adult, as two adults constantly do demonstrations as long as they aren't drinking, eating or sleeping.
Another option which works well is two adults and a child, the adults constantly demonstrate and the child occasionally joins in, the child doesn't fall behind because a less skilled dwarf gets way more experience from attending demonstrations, in fact they sometimes give demonstrations.
One could also consider locking up 1 or 2 adults and a large number of children in a room for long periods of time, one could come up with a name for this scheme such as "School", giving young dwarves a head start on a productive life.
Spooky education at a distanceThere seems to be no requirement for a Guild Hall to contiguous, it appears to be possible for dwarves to attend demonstrations "through a wall". This means for instance that vampires and werebeasts can be allowed to participate in Guild education without risking them eating other participants by just painting the guild zone over their isolation chamber. This could allow vampires and werebeasts to become elite educators.
Another potential use for this would be locking two dwarves together for "bootstrapping", but from time to time painting another patch of the guild hall outside to allow other dwarves to sit in on the demonstrations and quickly get their skill uplifted to the current state-of-the-art of the bootstrappers, without needing to re-isolate the bootstrapper dwarves.
One of the general issues with Guild Halls is "excessive attendance" reducing fortress productivity, and I think that spooky education at a distance could be a useful strategy in general, empty but beautifully decorated guild halls could be created and permanently locked up, this should satisfy the dwarves which want that Guild Hall to exist. When you actually want dwarves to participate in that guild you just paint some of that zone somewhere else allowing dwarves to attend, then when you want them to get back to work just un-paint it.