Breeding Zone and Walls of Mists respawn every time you enter them. Storing any items there is impossible.
Barrow Downs (exterior), Evermorn Island (exterior) and Lands of Giants (exterior) respawn every 6 months.
Castle Harmondale never respawns, even if it is upgraded twice. You can store your items in chests there as long as you want, even if the castle is upgrading.
All other areas, especially all interiors, respawn every 2 years.It is safe to store your items in any chest, crate, or case in MM7 - until the area respawns. On respawning, all monsters in the area are recreated, the contents of all chests in the area is discarded and lost forever, the chests are refilled with new random loot and locked.
The bank in MM7 is safe - well, if you made a deal with certain Mr. Malwick and if you failed to do a task of the Tatalia ruffians later, then not only Harmondale gets attacked by the ruffians but also all your money in the bank is lost. Anyway, why store money in a bank in MM7 or MM8? Money weights nothing and there are no thieving monsters around, which could make your pocket unsafe. Your pocket is the best bank, even the ruffians from Tatalia cannot do anything with your pocket 
