Final answer:
Insufficient mastery in certain areas can indeed slow future progress.
Step-by-step explanation:
The statement is true. Insufficient mastery in certain areas can indeed slow future progress. For example, in the context of education, if a student does not have a strong foundation in math, they may struggle in more advanced math courses or fields that require mathematical skills, such as computer science or engineering. Similarly, insufficient mastery in subjects like English or history can hamper a student's ability to write effectively or critically analyze information, which are skills needed in many academic and professional pursuits.