Honestly there isn't one universal strategy post that's going to fix this because "tough quant questions" usually means different things depending on where you're getting stuck, timing, silly errors, or genuinely not seeing the approach. What worked for me during my 725 prep was writing down, in one line, why I got a hard question wrong, not just redoing it. After a couple weeks I noticed almost all my "hard" misses were number properties and combinatorics, not because I didn't know the rules but because I was overcomplicating setups instead of testing small numbers or picking smart values. Once I saw the pattern I stopped grinding random hard sets and drilled just those two areas. For a starting point, the PS and DS question directories pinned at the top of each forum let you filter by difficulty and topic, that's more useful than a single "strategy" thread. Figure out your specific leak first, the strategy follows from that.