If the use of slaves and offering freedom or some other compromise were implemented in the early stages, maybe it would have gotten off the ground. Only if the 'owner' were in agreement. The Southern point of view was (as so many others still believe today) the "Big" government was to hold a limited role in the everyday lives of the citizens. Heck, there were men all over the place beating up and killing their wives but there was no major outrage on that. Local, state or federal government didn't deem that was worth spending a lot of money and time on. Some weren't even arrested.
With battles going on all over the Southern terrain, just how and where could things like training take place? Yes, they thought of it. Yes, they may have argued about it. Still, the 'principle' was the most important thing. If you ignore your principles, if you don't bother to remember them, you really are pretty messed up. Look at the state the Union is in now. This is what you get when you ignore the principles that kept you together for so many years. IF indeed, emancipating the slaves were the real reason the Union fought the war, seems like they forgot their priority and took quite a while to get around to it after the end of the war.
There is no definitive answer as to why Lee and others were not getting what they asked for. There was more going on in the seat of Government and Davis and others were not just twiddling their thumbs thinking "do we use slaves or not?" It may have been discussed and put on hold. That's another thing any government body will do. Don't care where they are.
Pam