Do not study for 2 hours straight. Study for 15 minutes, take a 5-minute break. The Shin Kanzen Master layout is designed for short, intense bursts.
The series (新完全マスター) is widely regarded as one of the most thorough and exam-oriented Japanese study resources, especially for the JLPT (Japanese Language Proficiency Test). The N4 Goi volume focuses specifically on vocabulary needed for the N4 level. Shin Kanzen Master N4 Goi Pdf