No time to look at 100 concepts. the AI could do most of that given prompts that take less time than getting the artist to your office... or if you include the directions to the artist then waiting I'm sure skipping them is faster. How about the artist looks over 100s of ideas and only brings the you the top few to decide since they are supposed to have taste and you are just the boss.
I could see a good IT person rigging up an AI to take a feed from the staff meeting brain storming the project and generate images live while the meeting is ongoing. That would create a faster more productive situation; possibly. The artist could play with that during the meeting.
Anyhow, I'm not saying having somebody managing appearances isn't useful but that you could do with just 1 person in that job. I don't think throwing more output at them would necessarily be a huge benefit... for ideas, 1-2 people is plenty. For cranking out results once the decisions are made, then a schedule and money decides how many artists are needed -- and for that aspect of the work the AI is a force multiplier where you use the 1-2 people to replace dozens. Or nothing changes and now you shorten deadlines because your highly productive artist makes that possible. Faster to market and no labor changes is another option. It also could mean they are done sooner and do not need to be employed as long so they become gig workers...