This is the most famous and widely-used set for rigorous practice. It is designed to build a strong foundation. The primary offering is the 3-volume "GATE MCQ Electrical Engineering" set.
Which (e.g., Electrical Machines, Power Electronics) you are currently preparing? rk kanodia gate ee
The sustained popularity of RK Kanodia's work stems from its structural layout and pedagogical approach: This is the most famous and widely-used set