A flush is a great way to loosen-up and wash away the salt build-up, which affects your ph, your nutrient uptake, and general overall health.
Flushing often is not recommended. I do it done once a month, or every 6 weeks from veg, thru flower, using approx. 3 times the volume of water that will fit in your pot, of properly ph'd water. (takes about 5 minutes per pot) Let it drain well, and no more water till soil dries out, or you risk root rot.

Limited yellowing of the fan leaves is normal, deep into flower. If it's yellowing elsewhere on plant, likely she's having other problems, too.