I haven't seen any evidence of salt buildup in the growing medium, especially if you are watering to runoff every time. To make a categorical statement like, "The problem is accumulated salt in the medium." It assumes that every grow has that problem. I disagree. There is no build-up of anything if you water to runoff.
In veg you let the plant dry further than you do in flower to encourage roots to grow in search of water. In flower you want the plant to have a constant source of water to help grow the flowers. I water a day earlier in flower than in veg.
I always water to runoff as well. Just faster than Emilya does or I'd have to quit my job
.