Neil Gaiman's The Sandman ran for 75 issues; there was one "special" issue which told Orpheus' story, but it's not numbered. According to Neil Gaiman in The Sandman Companion, he was intending to end the series at some point, but it's not clear whether he intended the series to run for exactly 75 issues
Mike Carey's Lucifer - which uses the character created in The Sandman and shares the same continuity - also ran for 75 issues; it had a 3-issue comic The Sandman Presents: Lucifer - The Morningstar Option, a one-shot Lucifer: Nirvana, but those are, again, not numbered.
Both comics were published monthly, so I understand that they ran for the same amount of time (~6 years) - but what is the reason for that?
Is it purely a coincidence that the two series ran for exactly 75 issues? Was it a homage from Mike Carey to Neil Gaiman, and the series Lucifer originally was a spin-off from?