I advised my mentee to save both the current production source and object programs and to pilot-test his project before he committed it to production.
Saving both the current program source code and the program executable object program almost always allows for rapid recovery of a failed programming change by using procedures found in the project implementation turnover documentation. Many programmers do not bother to save the current production executable object program before overlaying it with the new object program, thinking that they can quickly recompile the saved source program. Then they find out that they cannot easily re-create the object program when the new one fails, because something is not exactly the same as it was long ago when the original executable object program was last compiled perhaps disk file format changes, or a library list error where the incorrect libraries and disk file are referenced. That causes intense and unnecessary stress on the programmer from IT management and the end users. I have seen programmers lose it when they cannot figure out what is wrong when a project backout is required.