You mean for predicting what happens. Sooner or later, you have to try it, why not sooner? There are times when one learns more by trying something and then searching for the reason it didn't work. I learned more about integration by parts by trying to use a published equation that had an error. It turned out to be a typo, but I had to go through the pertinent aerodynamic equations to find that it was a misplaced absolute value sign.