Depends on your level. I personally have thrown myself in the deep end with reading starting from complex fantasy stories and have learned how to distinguish between words really useful and those I could leave out. I think this is the key to get over with a fact that it's impossible to pay attention to every detail and not get bore to death. Reading should be enjoyable and as long as you understand let's say 80% of each page, your are fluent-reader - as you come across some unkown expressions you will finally absorb them. Plenty of them are really unnecesary for daily life and even natives deem them weird or quirky.