By my way of thinking, you must find the cause of the puncture, whether you patch or replace the tube. The easiest way to do this is to pull the tube out of the tire, before removing the wheel from the frame, and inflate it. Once the puncture is located, you can assess how easy it will be to patch it. If it's going to be complicated, replace it; if it's straightforward, patch. It's also really easy to find the cause of the puncture at this point. While the glue is drying you put away most of the tools, remove the debris from the tire, boot as needed. Very little time is wasted; and the job is done.

If I'm in a hurry, maybe I can save a couple minutes by just replacing the tube, but it doesn't always save time. Sometimes it's worth the gamble.