[Graeme Dice]

Originally posted by Zapmeister:
What I meant was, filling up the table either prevents the casting of further GEs or it doesn't (I'm not sure which).

It doesn't do either. When there are five global enchantments each new enchantment must overpower an existing enchantment in order to take effect. Thus filling up the list makes it harder for new enchantments to take effect, but also allows for new enchantments to push out old ones.