a direct criminal appeal is completely useless without the trial attorney making doubly sure that any appellate issues were properly preserved for the appeal or beyond. In this sense, what you don’t know can hurt you, badly. And you must have lost and been convicted (otherwise, an appeal has no purpose).
By design, it is the jury’s solemn responsibility to doubt everything and make the government satisfy the constitution’s extreme requirements. In this regard, a trial should be an exceedingly difficult proposition for the government regardless of its evidence.