What is the number of times Beetlejuice's name must be said by characters in the film to summon him?

In the film "Beetlejuice" (1988), the number of times that Beetlejuice's (Betelgeuse) name must be said by others to summon him is 3 times in a row. The movie's plot revolves around a recently deceased couple, Adam Maitland and Barbara Maitland, (Alec Baldwin and Geena Davis) who become ghosts haunting their former home. There is also present an obnoxious, devious poltergeist named Betelgeuse (spelled Beetlejuice). He is portrayed by Michael Keaton. He comes from the Netherworld and tries to scare away any new house inhabitants (Catherine O'Hara, Jeffrey Jones, and Winona Ryder).

In the film when dealing with Beetlejuice, it's apparent that saying his name three times must be within some measure of proximity. For example, please note the following:

When the Maitlands first find Betelgeuse's business card, Adam (reading the card) says his name out loud twice but the third one is torn away. Days later, after they've met Betelgeuse (Beetlejuice) in person and decided not to use him, Adam says the name again but nothing happens.

Juno says the name at three different times throughout the film, but only twice in the same scene. Nothing happens the third time she says it.

Barbara Maitland also says the name several times throughout the film, but it only has an effect when she says it three times in succession. So, it doesn't appear to matter how much time passes between utterances of his name, so long as there is a genuine 'intent' to summon him.