Surgery:does it really do any good to worry prior to a major operation or the possible outcome afterwards when plans are made and the surgeon trusted?

It does no good: Worrying is natural, but does no good because humans cannot predict the future. As the saying goes, que será, será. Whatever will be, will be. For example, we don't know whether or not a worried person driving slightly faster, will end up in an intersection at just the wrong time (and get broadsided), versus an UN-worried person driving slower, ending up at that intersection after the accident.