Strength is a relationship, not a compliment
Day Master strength describes how supported or pressured the central element is inside the chart. It is not a measure of willpower, moral quality or life success.
The first question is season
The birth month and solar term context show whether the Day Master is in a supportive climate. Roots, hidden stems and surrounding elements then refine that first impression.
Strong and weak both need design
A strong Day Master may need outlet, responsibility or discipline. A weak Day Master may need support, pacing or resources. The point is not to rank people, but to find the environment where the chart functions better.