Especially on something difficult or sensitive.
That way, your listener will know right away what the situation is.
And they won't have to feel like they're searching for the proverbial needle in the haystack while you go through all your detailed explanations and only then say what the issue is.
Gopal Kapur, founder and president of the Center for Project Management (and member of the Harvard Policy Group and Project Management Institute, among other things), has given us a simple communications series. It focuses on giving the most important information first, so the other person can better understand what comes next in turn.
And it shows respect for the other person as a grownup who (1) can handle bad news and tough issues, (2) can sift through and discard all the whipped cream* to get to the truth anyway and (3) has other important things to do in the time you save them by skipping said whipped cream.
[*] Whipped cream seems to hide what's underneath, but you can brush it aside and find what's below...with time and mess. It may be fine on your sundae, but skip it on Monday!
H/T: Douglas R. Wilson.