A corollary rule is what makes a problem go away. I was pulled into a war room situation on a remote call (pre Zoom days) to debug a problem where after some digging it seemed some variable was being corrupted deep in the code. I suspected it might be a scope issue with two variables with the same name in different functions that the author thought were separate but which were actually one value. I descended the function tree from the top changing every variable "i" to something unique until luckily the problem went away. Made my boss happy.