Reza Rad shows us an extreme case of variable fatigue in Power Query:
This is a sample Power Query file, which in that I do a very simple transformation. The transformation is adding one to the existing number. However, in this sample, we are doing it over thousands of steps! one step at a time, we are adding thousands to a number. The main reason to do it this way is to show you what is the performance you get when you have too many variables (or let’s say steps) in Power Query.
Reza reduces the number of steps and turns a 15-minute operation into one which finishes in under a second.