One of the major causes of crispy fried plants with yellow dying leaves at harvest is from overfeeding. In many cases the nutrient strength some companies have you feeding according to their charts are ridiculous. If you follow Fox Farms chart and use all their products they have people feeding as high as 3.3 EC / 2300 ppm. Then flushing every few weeks with another one of their products to remove salt buildup. If they didn't have people overfeeding to begin with there wouldn't be any salt buildups.
Some people use the term 'Fade" and say it's normal for leaves to be dead and dying at harvest. Some yellowing and leaf die off is normal. But the pictures some people post of completely fried plants that look like total crap get accolades from some that say "Nice looking plants". It's become obvious that many newer growers don't know what a healthy plant at harvest should look like.
Feeding correctly with a balanced nutrient is important for healthy plants seed to harvest. Many go into bloom and go to extremes with high P/K and completely cut out the nitrogen. Anyone with a minimal understanding of plant physiology knows that nitrogen is required for all stages of a plants life and is needed for the production of chlorophyll and the process of photosynthesis. Extreme yellow leaves are exactly the opposite of what you want in a healthy plant and maximum flower development.