Kips and PIS smart book

Bro I’m lowkey stuck 😭 I wanna buy the PIS Smart Book set because I need more MCQs for the chapters I’ve already practiced. The problem is it comes in pairs (Bio + Chem and Phys + Eng), and I mainly want Chem and Phys. So it feels like I’d have to sacrifice one subject just to get the other. The thing is, I already have the KIPS Chem, Bio, and Physics books. I’ve solved some chapters from them, but I want extra MCQ practice for specific topics. That’s why the Smart Book is tempting. But then I keep thinking: what if I buy it and barely use it? 😭 I’d feel so guilty for wasting money. Now I can’t decide whether it’s actually worth buying or if it’s just an impulsive ‘I need more resources’ moment. 💀