Temple of Ranma's Sailor Senshi Seifuku

Thanks. Any ideas/comments why they so seldom appeared in "human" form?

Working on an idea for a fic, but was looking for some clarification on something first. I've read that Aretemis and Luna can transform to human shape, but would like to know. 1. How long can they stay that way 2. Does it take effort to maintain the form 3. Is the form just an illusion/temporary for...