I’ve always avoided agreeing to a time frame for a discussion. “Can I have a half-hour of your time?” “No, just tell me what your question or issue is.” I can usually take care of the inquiry in five minutes. Otherwise, the person will try to fill the 30 minutes.
Conversely, when I find myself obligated to a meeting, I say, “I’ve allocated 30 minutes, so let’s get moving.” People then are highly sensitive to the time and will comply and move faster. (The danger is that if you don’t abide by your own limit and go beyond with the discussion, then future limits will be ignored.)
Why is this so important? Because I’ve found I can always make another dollar, but I can’t make another minute. And although you may see that appear on social media without attribution, it’s from my books and my work!