The life cycle of a CM meeting engagement

[kineas]

I'm usually not much for keeping a reserve until late in the fight, my theory being I'm better off with everything in the fight I can bring. If I can fight my opponent even with 80% of my forces for 25 turns, and then crush him with a reserve, I could have crushed him even sooner with 100% of my dogs in the fight.

You use the reserve to decide fights, the whole point is that you have a bunch of units available for commitment at the decisive moment. If you throw it in early you probably won't decide anything. You'll win a fight what you would win without the reserve, or you'll reinforce failure and lose the fight together with your reserve. You commit the reserve when you know you need it.