Adaptable Practice Questions Difficulty

soo.. in these practice questions, solving level 4 questions ( which here showing as "your level" 3 for T & W ) means, we are solving the Hard Questions which are usually marked as "Hard" in Mock tests ? i wanna know this because if level 4 are of Hard, and level 3 are of medium, then i will first solve all the chapters till level 3 and after completion of all chapters till level 3, i will do level 4 if time is still there.. so, two questions, "does level 4 questions means those difficulty level where they are marked as "hard" in mock tests ?" and second question "is my approach of solving all chapters till level 3 first before touching level 4.. is that good ?"