It probably helps that siege is a pretty skimishy game mode anyway. If I was In command of a "company" (lets say 20 people) in an assault Id probably just have a flag carrier drop a flag at a well covered forward point and sally from there whenever we get enough of us assembled, you cant keep a line in these kinds of situations even if you wanted to.
On defence its mostly just a question of making sure all the avenues of attack are guarded, people with loaded guns want to fire them and people without want a safe place to load, the rest handles itself.
Ive actualy been reading up on the actual napoleonic war and lots of historians like to remind people of the very common use of skimished infantry (loosely spread out). The advantages of the line is weight of fire against other lines and immunity to cavalry. Though the french had this technique where skirmished infantry was paired up, firing in turn, that way they were less likely to get caught with an empty musket.