na-adjective
Describes an approach, process, or person that follows a systematic method or procedure.
彼の仕事のやり方はとても方法的だ。
His way of working is very methodical.
この問題には方法的な
A procedural approach is needed for this problem.
体系的 means 'systematic' and emphasizes a structured system, whereas 方法的 focuses more on following a method or procedure.
Compound of 方法 (ほうほう, 'method') + 的 (てき, '-like, -ical'), forming an adjectival noun meaning 'methodical' or 'procedural'.