Your understanding of the functionality is correct. There are a couple of criteria that drive when a bin is "done." In this case, if you establish the optional maximum properties, these drive in closing out sooner. That is if a max age is specified, and any of the bins have gone beyond that time, they will be closed and transferred out.
Alternatively, a bin is also considered ready if the max age has not yet elapsed and:
* both minimum size and minimum number of files has been reached and a few successive attempts to add to the bin (specifically, five) have been unsuccessful, signaling that it is nearly full or the objects are ill suited for tighter packing.
* size or number of entries is greater than or equal to their respective, optionally, specified maximum
Let us know if you have any other questions!