I think I am rather experienced in English. So I am reading a book, a novel, I write down the words I don't know. I did that for half a year or so. Then just for fun, I was downloading some pronunciations of those words to see if I could place them on my mobile phone, and learn them when driving in my car. I was astonished to find out, that about one in twenty are pronounced differently than I thought. Okay. It are mainly 'snobby' words coming from French for which mostly there is a more common synonym, but nevertheless. So, even as an advanced speaker, you should check all the new words you are learning.
Do you always check them?