It’s not about the raw time wasted, but more about the interruption. When people are concentrating on some creative task, having this one-minute gap between “hello” and actual-question can really break one’s “flow”.

Much better for the question to be directly asked, so that the person can respond asynchronously when at a convenient stopping point.

Also note that asking directly doesn’t preclude being polite with “hello - mind if I ask you a question? <insert question>. Thanks in advance!”