He says it automatically, at the end of a call, at the door, in the hallway, whenever two paths split apart. The words come out before he can think them through, they trigger themselves, like a light switching on from motion. Nobody called them. They arrived on their own.
They mean nothing specific. They wish nothing definite, no health, no happiness, no particular thing he actually wants for the other person. It's a sound that fills the gap where a real goodbye should be, and nobody notices, because everyone knows that sound and expects it in the same place every time.
He uses it on a coworker he barely knows and on someone he genuinely cares about. The difference between them disappears into the same phrase, as if it didn't matter who those words belonged to. Two different people, one identical echo.
Words that were supposed to carry weight get brushed against the teeth and vanish before they mean anything at all. A real wish requires attention. It requires knowing who you're speaking to, and what you actually want for them. It requires stopping for one second and looking at the other person as a person, not another checkbox in a list of goodbyes.
The phrase needs no attention. It works without it, works constantly, works even when the other person stopped listening long ago, works even when spoken into empty air, because its only job is to keep the silence from feeling awkward.
And so people walk away from each other with words on their tongue that said nothing, and nobody finds it strange, because that's how people say goodbye every day, over and over, without either of them remembering what the word was ever meant to mean.