n. Going too far with a project, or not knowing when to bring a project to a close.
2000
[The] banana problem…applies to when Web site designers don't know when to call it quits, resulting in an overload of bells and whistles, as in In an attempt to retain their target market's short attention span, the TeenCool Co. Web site had developed a real banana problem.
1993 (earliest)
Right now the publishing industry has a banana problem with books about hackers: it can't seem to stop publishing them.
This phrase comes from the story of the little girl who said, "I know how to spell 'banana,' I just don't know when to stop."