I found, often it is actually faster, after a very brief discussion, to just do what the client wants and let them (or you) realize that they were in the wrong. Then reverse it without being smug "I told you so" about it.

E.g years ago on a complex web form I got the feedback from my client's client, that because their boss was colorblind and couldn't recognize the yellow/orange borders for missing required fields (iirc), those fields should be greyed out instead. I wrote back something on the line of "Very valid reason to make a change, but my concern with greying them out is, that this is how commonly deactivated/disabled fields are shown in which you can't enter anything at all". I got told that this doesn't matter, I have to grey them out. Which I did without additional comment, sent them the new version and couple of hours got the response to undo it again and find another solution. In the end everyone was happy.

Obviously in this case it was something that only took a few minutes that can easily be reversed, but I often see people spending way more time debating on things (and not seldomly getting unnecessarily emotional) than it would take to just try out a couple different solutions and giving people something more tangible.