I actually read the clues and filled in the spots, though not all of them. You'll find that you can kind of just play the top row and be fine. Full disclosure: the puzzle was a 4x4 with a high success rate.
As for the clues, the repetition of it all allows you to avoid having to think much about them after reading: you just have a sense of where to put the marks. Another added benefit is that you start remembering the wording of previous clues so that you can combine them on the fly. As Hans and Franz would say, "Hear me now and believe me later"; you can definitely hit the low 100 second range with practice and it's that repetition that really works wonders without you even knowing it.
Now, when I first started playing here I couldn't get below the average to save my life. However, over time you will start beating the average and find yourself getting at least 300 points on the games with success rates of 50% plus. I still struggle to get fast times on the games with <30% success rates, but it's getting better.