Any time you are developing new content that will include objects players must/will collect, and said objects are expected to be collected/produced/etc in quantities greater than 5, and there is no difference between individual objects
MAKE THE DARN OBJECTS STACK FROM DAY ONE!!!!!!!!
Please print this post and hang it in your cubicles for future reference. And while you're at it print/copy some for your neighbors. And make a note of how well your printer/copier stacks the copies for you!!