JoeReal

That is quite true. If you have a large banana, let us say my Dwarf Brazilian which is about 4-5 ft at the trunk right now. It spits out more than one full large leaf (about 4 ft long leaves) per week. The broad, long, graceful leaves reaches full size in just 4 to 5 days for my plant at the moment. It is growing like crazy this summer when temperature is between 85-95 deg F. So most likely, they referring to the growth of the leaves and not the plant. Although last year, I have a plant that grew to more than 4 ft at the trunk in just a month, which can be interpreted as 4 to 5 weeks, and depending who you are, the number 4 to 5 is few.

Of course if your banana plant is a Tissue-cultured sized plant, there is no way it is going to happen.