Its not prefacing it with a summary, its letting them know you have a point at the end they should wait for.
I actually prefer the type of conversation that goes back and forth and tangents, but there is a place for more long form cohesive ideas, and you should wait to hear it all before speaking.
If you are going to make a long winded statement, its not crazy to preface it with something.
But then they think they heard the only important part already and miss the context which equally matters.
Its not prefacing it with a summary, its letting them know you have a point at the end they should wait for.
I actually prefer the type of conversation that goes back and forth and tangents, but there is a place for more long form cohesive ideas, and you should wait to hear it all before speaking.