Which of the following is NOT a common rule in spelling?

The statement "E always follows T" is not a common rule in spelling. While there are numerous words where "T" is followed by "E" (like "the" or "time"), it is not a consistent or reliable rule. Many words do not adhere to this formation, such as "stop," "bat," or "cat."

On the other hand, the other options represent widely recognized spelling conventions. The phrase "I before E except after C" provides guidance on how to spell words like "believe" versus "receive." The statement about the letter "Q" indicates that it is almost always paired with a "U," as seen in words like "quest" or "quick." Additionally, the rule stating that "S" never follows "X" implies that while "X" often appears at the end of words or combined with other letters, it does not precede "S" in standard English vocabulary (for example, "exit" or "box"). Thus, "E always follows T" does not fit within these established spelling guidelines, making it the correct answer to the question.