False
- Surnames were used long before they were commonly recorded. You will probably not be able to trace back to when surnames were first used. (There are some exceptions, for example the early Dutch in America.) So how your ancestors got the name will not help you find them
Before this century, spelling was not important, most people could not write, and foreign names were mangled or contorted. Over the many years since your ancestors first started using a surname, it could have changed in was you could not know. for these reasons, saying something like, "Our Elliotts have always spelled it with two L's and two T's" may mean you'll miss some important clues.
and don't forget that the surname you have is not the surname of all your ancestors. It is, in fact, your least reliable line, but often the one pursued most vigorously by men (yes, men) who are newcomers to genealogy.