I know that it's redundant to say things like "8:00 A.M. in the morning" or "6:00 P.M. at night." But what if you want to specify that you're talking about a specific night, such as last night? For example:
We met them at the airport at 10:00 P.M. last night.
Would this sentence be redundant? It seems strange to have both "P.M." and "night," but leaving out "last night" would change the meaning of the sentence, since it would no longer make clear what day this occurred.