If true, would this not point towards avoiding such unions in the future?
No, it just points to a. Having a reasonable exit process (the default of two years makes no sense) and b. The public having the patience to understand 40+ years of cooperation can't be rolled back in a matter of months.
Also they did not have to lodge the article 50 letter when they did, they could have spent years preparing and figuring out what it is exactly they want to accomplish.
Finally the EU gave an extension twice now for them to figure out what they want, instead of doing that UK govt doubled down on stupid.