Beetlejuice Beetlejuice might be the new record
This old question (originally asked a decade ago) produced some interesting answers, though some were beset by issues about what unequivocally counts as a sequel and one that uses the same actors for the same characters. And many of the answers were very obscure.
2024 saw the release of Beetlejuice Beetlejuice which is unambiguously a direct sequel to Beetlejuice which was released in 1988, a gap of 36 years. Many of the original cast return to play the same characters (notably Winona Ryder and Michael Keaton). It even has the same director, Tim Burton.
It is a direct sequel to the original (not a latest release in a chain of other sequels).
This seems to be the new record for a well-known mainstream hollywood production. And possibly the record for direct sequels.
PS As pointed out Gendolkari, There is another clear recent example that equals the Beetlejuice record in years: Top Gun: Maverick. It was released in 2022, also 36 years after the original movie it is a direct sequel to. But on US release dates (HT iandotkelly), Beetlejuice 2 wins by about 5 months.