From Dr Eric Mascall:
"It is a mistake to suppose that there is nothing in the Eastern Orthodox Church like the private masses of the West. I have known an Orthodox priest celebrate the Liturgy for thirty successive days for the soul of another priest who had just died. On many of these occasions there was only one other person present who acted as both 'server' and 'choir', and on some of them the altar had been used immediately previously for another Orthodox Liturgy. The priest in question told me that this custom was quite common."