Functional analysis and real analysis are essential areas of mathematics that have significant applications in theoretical high energy physics research. While they are not purely abstract, they provide foundational tools that can enhance understanding in physics, particularly in quantum mechanics. The allocation of time for learning these subjects varies based on individual needs, interests, and levels of mathematical proficiency, with suggestions ranging from 3% to 30% of overall mathematics study time. For those with a strong mathematical inclination, starting with functional analysis can be beneficial, while others may prefer to approach it alongside quantum mechanics. Ultimately, the focus should be on personal interest and relevance to one's research goals, as a more physics-oriented approach may allow for a selective engagement with mathematical concepts as needed.