Ok, I know that question was rhetorical, but let me explain what got me thinking about it.
I'm planning a May 2019 trip to Great Britain with my partner and another couple. We had a dinner meeting this week to go over what cities and sights we were most interested in. Having taken multiple overseas vacations, I would say I fall into the "rigid planner" category. I enjoy researching attractions, hotels, and restaurants with the idea my trip will be jam packed with tons of amazing moments and memories.
The couple we are going with don't seem to be hardcore planners, and are more inclined to be happy "discovering" things by chance. (Of course we both have major sights on our list we are mutually interested in.) They don't really have must sees per say. They mentioned how they had the most incredible meal in Italy in a local's only type of restaurant they stumbled across.
So my question is, how do you balance "minute by minute" planning with just letting things happen by chance? I'd love to hear about a chance happening on one of your trips and what led to that "happy accident" :) Cheers!