This was my first cycle really using OPKs. (I ran out too early the first time I tried, and never saw a positive.) Because of that, and because I don't temp, I kept testing way past when I thought I got my positive. I wanted to make sure it was a clear surge. I am now 4-5 DPO (got my positive OPK on Wednesday, but could have actually ovulation on Thursday) and my tests are steadily getting lighter. I like watching the progression, as it makes me feel like everything is on track. I may change my mind once this cycle is over and I have a good sense of what my LH levels are like. You may not need to test past your positive OPK if you already know a bit about what your cycle is like. If you're feeling unsure, though, then it wouldn't hurt to continue testing.