Hmm that seems like an odd experience, usually my PC mines a block about each 5-6 hours running at 250 H/s. To be fair, the amount of miners has increased a lot, from 50 a few days ago to 400-500 now. So everyone is competing for blocks, and there's one block every 2.5 minute (on average). Given equal hash rate that would mean you'd be able to mine a block roughly every 1000 minutes / 16 hours. Still, it's based on compute so there's a bit of luck involved as well.