Menachot 50: Morning and Afternoon Sacrifice and Ketoret Offering

In the morning and then in the afternoon, daily sacrifices were brought to the Temple along with the the ketoret, incense offering.  Yesterday's Mishna described a disagreement about whether a specific sacrifice or the ketoret was offered in the morning.

The Tanna Kama permits the afternoon korban, sacrifice, to be offered at its proper time if it was not brought in the morning.  Rabbi Shimon permits the afternoon korban only if it was accidentally forgotten in the morning.  Rava says that the kohanim are punished if they do not bring the morning sacrifice and then other kohanim bring the offering in the afternoon.  

If the ketoret was not brought in the morning, the Tanna Kamma allows it to be brought in the afternoon as usual.  Rabbi Shimon says that the full amount of the ketoret is brought in the afternoon if the morning half was forgotten. The Gemara explains: since the ketoret was unusual and the person who brought it would become wealthy, it was never forgotten and the kohanim were never punished.  

What does "unusual" mean?  Rashi says that the korban was a form of a common burnt offering  while the ketoret was unique and limited to two daily offerings.  In Masechet Yomi, we learned that no kohen would deserve to offer the ketoret more than once in his life.