In a compound sentence (one with two or more verbs, each with its own subject), the sentences-within-the-sentence should be separated by commas.

The meeting runs from 9 am to 5 pm, and lunch is included.

I’m good enough, I’m smart enough, and people like me!

Commas are not necessary if it isn’t a true compound sentence:

The meeting runs from 9 am to 5 pm and includes lunch.

There is no rule against using commas in a non-compound sentence, however. Especially if the sentence is long, it might call for a comma or two as a “breather” for the reader.