This frequently asked question has a case by case answer.
Every student is unique. Learning style as well as progression speed also vary from person to person.
Generally speaking, if the student follows the intended, customised program that his, her, or their instructor has set, recognisable improvements will definitely show in due time.
What is more, we can always revisit the assessment phase if necessary. We strongly believe that there are often complex set of factors that contributes to poor performance. It is therefore acutely important to try and understand the causes of such lagging. When we re-examine the root of the problem, we become better equipped to help the student further.