Very interesting article. Bulb size is a result of the cultivar; miniature and cybister ones are never going to make huge bulbs. Some cultivars don't increase much in diameter over the years, instead they produce lots of bulblets. Supreme Garden is a great example of this, the mother bulb, which doesn't get much bigger, produces a clump in a few years. But in general, you expect that age will also result in bigger bulbs, if there is adequate water, sun and nutrients during the growing season. The "jumbo" bulbs, some are retired mother bulbs and some have been left in the ground for an extra year or two, are much more expensive due to production costs. You expect them to produce 3 or more scapes.
