I think I've found a bug, or an unintended feature.
When you research Leadership, and enable Garrisons, it "Replaces the Archery range" OK not a problem, but it doesn't give experience to Archery units.
They have gone from a situation of +3 Experience with Archery range, to Zero experience, with a garrison.
Archery ranges dont' obsolete till Rifling,
Now in New cities, I can't build an Archery range, only a Garrison, for no additional experience for Archery units.
Archery ranges have been 'obsoleted' by the Garrison, but I can't build Arquebusiers till matchlock, so I now have a unit, with no additional expeience, apart from settled Great Generals, that doesn't obsolete till rifling.
Archery units upgrade to Arquebusiers
*Edit*
Melee units don't gain expeince from a Garrison either, and Garrison has obsoleted the Barracks
So what's the solution??
1) Obsolete Archery ranges at Matchlock, and remove replacement from Garrisons.
2)(i) Melee units to gain experience from Garrisons as well, +3 same as Barracks.
2)(ii) Reduce both Garrison and Barracks to +2 for Melee units, as Gunpowder only gain +2, but as more powerful, seems a good trade off.
Simples *Scheech*