Spent time last night playing the single player "Landing Zone" and flamed my way into the lower AI spawn room. Once there, the spawn rate was so high that two new AI characters would spawn before I could kill one of them. I think that this spawn rate is a bit high for a single player vs. AI game.
I also think that spawn points should be out of bounds for enemy units unless the game type is capture the flag. If the spawn rate had been lower in my games last night, I could have stayed there and picked them off. This could also prevent team killing where an enemy player camps on a team's spawn and prevents things from progressing.