Okay, now that I've learned a lot about my attic, another question came to mind.
On the subject of collar ties, why would they not be put on every rafter? Reading a bit online about this subject I came across the references about how some codes mandate 4 feet between them (approximately every other rafter). Why would having them on every rafter be a bad idea? Seems like putting them on all rafters would do a lot toward strengthening the structure.