I'm surprised to see there hasn't been much discussion about using the first GG as a "can opener".
Attaching a GG to a unit is definitely a good thing to do in many games so you can unlock the Heroic Epic (and/or West Point) with ease, but more often than not I'd probably make a strong combat unit than a super medic if I'm going to attach at all.
If you play a Protective leader, attaching a GG to a 6xp+ longbow or crossbow could be a good idea. "Why?" you ask. Not as a can opener but an xp-earner. 26xp allows Drill IV and 2 extra promos. Take Leadership and then perhaps tactics.
EDIT
Sadly, Leadership extra xp does not count towards the next GG.
Attaching a GG to a unit is definitely a good thing to do in many games so you can unlock the Heroic Epic (and/or West Point) with ease, but more often than not I'd probably make a strong combat unit than a super medic if I'm going to attach at all.
If you play a Protective leader, attaching a GG to a 6xp+ longbow or crossbow could be a good idea. "Why?" you ask. Not as a can opener but an xp-earner. 26xp allows Drill IV and 2 extra promos. Take Leadership and then perhaps tactics.
EDIT
Sadly, Leadership extra xp does not count towards the next GG.