Dear xzins,
Actually, it is my understanding (although I may be in error), that to teach folks in the seminary, actual priests do re-enact the Mass with seminarians to teach them how to celebrate the Mass, but without the intention of confecting the Blessed Sacrament each time.
sitetest
Having been a seminarian — though not Roman Catholic — there’s nothing that is led by an ordained Professor that is viewed as simple practice. The environment of seminary changes it. I’m probably presuming too much, my coming from a protestant setting, but I remember seminary being “holy ground” for want of a better way to describe it.