yup t/m definitely are aid stations
but their thief and magic power are equally important. they are needed to bring down key targets
attackers are definitely needed for war, but good use of t/m can WIN a war.
as for optimum numbers, i find 3~4 to be good numbers depending on setup (with 4 t/m u r guarenteed with at least 2 t/m staying safe, whereas if u keep 2 or less u risk loosing them both and having no t/m. more than 4 is too many)