There are plenty of cases in real-life. Look at airplane accidents. Many times a variety of small little issues and deviations then lead to one big incident, usually a crash, involving loss of life and property damage.
Mark and I have learned this the hard way too. When we started working together as a team, we also developed a very rigorous check list and procedure list. We kept refining this list, adding items to it, taking some off, re-wording certain items. And here is the absolute truth:
Every time we do not follow our own advice, our own procedure list, that's when we start getting into trouble. The moment you let go of incorporating your past experiences, you are increased the chances of failure tenfold.
The other very important lesson is that there usually are a few small things that don't go as planned, all adding up and ultimately contributing to the "main event", i.e. the crash.
For example, the battery for the camera going daed 3 minutes into the flight. Now you are forced to return, land and exchange the battery. Right away you are doing something very different from your normal procedure. And to be in this situation, you probably already did not go over the check-list in the first place; "Insert fully charged battery into the camera" was clearly not followed.
What looks like a simple flight interruption, can now turn into a chain-reaction. You are out of your element already having to deal with this unexpected interruption. Unless you regrouped and start fresh, you are with no doubt increasing your changes of additional issues. Why you might ask?
Let's review this a little further.
After 3 - 4 minutes of flight time, what do you with the main battery? Do you keep it strapped on or in your machine and fly more, since you should be getting twice or three times the amount out of it? Or do you exchange it with a fresh battery?
Guess what you are supposed to do - and you would if you followed your procedure carefully. You would take the battery off and grab a fresh, 99% charged one and put it on your flying machine. Not doing that, will again, cause you additional issues down the road (well, the air), because you are doing something different and out of the norm.
Long story short - the best scenario that could happen to you after not following your own procedures is that you land in a tree or a field; softer and without impacting others. But sometimes there are no trees close-by. It could be water, concrete or a building.
Create your own checklist and procedures and stick to it. All the time! If something seems out of norm, start over. From scratch.