*Hakim* said:
but your basically forced to fight in open battle to up grade your units....
Not true at all. To build a strong large army, the most important skill is
trainer - and it is the only skill that is worth having on ALL your companions. It only applies to units that are lower level than you, so it is less effective when you and your companions are below 20s, but later it is the most valuable skill you have. It means that your recruits go from tier 1 to tier 4 in 3 days while doing NOTHING. Tier 5 takes a little longer, but since tier 4 is level 19/20 all trainers above 20 will finally get them there.
Pump all you companions with trainer skill and by the time you finish your recruiting campaign ("Here! the mead is on us!... how about you sign down here... your hand is wobbly, I'll help you do it") and travel to the action, all your units are tier 4-5. Companions have little direct contribution to the results of engagement. Trainer skill is where they really can make a difference by making everyone else fight better.