Had a thought. Earrings are the lightest thing, and featherwood is the lightest material. Why not test coinstar in 43.03?
Setup, after month inside:
The earring squares are also 1 tile retracting bridge/ramps, per the old coinstar setups. Dumped in 32 earrings, and set 3x3 meeting zone on lever with do it now/repeat. Not perfect, but...
Before and after the month in it:
That is 193 attribute points, spread primarily over Agility, Endurance, Kinesthetic Sense, Spatial Sense, Strength, Toughness and Willpower with less in Focus, Intuition
They also gained exactly 750 experience in armor user, over 21,8 pages, with something like 1 to 3 ratio for slamming into an obstacle versus taking a hit from earring - suggesting 187,5+17,58*#Earrings exp per month.
The dwarf got no injuries, but satisfied needs of skill practice, martial art and learning.
Doing similar test in 43.05, I get a segmentation fault without getting to see even a single combat report.
Now, we know about wear-related crashes in trap components, but...Still. Not sure if the cause is earrings hitting the dwarf or dwarf hitting the bridge (building damage). Suspecting that Toady didn't handle combat wear for anything not weapon or armor for this minor tweak.
Edit: It seems that getting the expedition team to loop minecart dump 5 earrings onto themselves (via ramp/stockpile/non-location meeting area in the hole(probably decreased effectiveness due 4 animals and 2 visitors in hole)) is far more effective, producing following experience increases over a month (start is not 0 due not starting to record at 0)
237->2043
60->285
0->9
102-> 534
21->738
0->9
117->3069
Though obviously this uses up more dwarf labor (but on the bright side, no danger of dropped sock jamming skulls through brains). I suspect the uneven gains are due 5 earrings and 7 dwarves leading to two dwarves getting the bulk of total 6150‼ experience points.