Recently Orthocath, a fellow blogger, published a very nice article on the Eastern Orthodox usage for Prosphora bread versus the Eastern Catholic usage that has developed as a result of latinizing tendencies. It is an excellent article on various details of the Proskomedia, the theology behind it, and the usages that have developed. One of the details that Orthocath points out is that when the Lamb is cut out of the Prosphora loaf by the Eastern Orthodox, all communions come from only that one Lamb, regardless of the size of the congregation.
This could create a problem with very large celebrations, except that the obvious answer is to simply cut out a bigger Lamb when the congregation is larger. One can even bake larger Prosphora breads in order to increase the size of the Lamb that can be cut from it. In support of this, Orthocath makes the following commentary to which he attaches a photograph in proof of his commentary:
In Orthodox churches this use is unchangeable even in situations where an abbreviated method might speed up the Liturgy or make things more convenient. The same procedure is followed for every Liturgy though the size of the Lamb might be adjusted. For example, notice the size of the Lamb at a recent Liturgy in Ukraine which was attended by thousands of worshipers. A few of the tiny commemorative particles can also be seen next to the Lamb.
Father Orthoduck must admit that he gasped when he saw the size of the Lamb and of the chalice next to the diskos. His impious mind immediately wondered WHO would be the poor deacon that would be expected to hold that chalice during the communion of the faithful. And then, his even more impious mind wondered whether those were actually a normal size diskos and chalice, and he was looking at a photograph of Ukrainian Orthodox hobbits!