I go with 1/2 strength twice a week, mainly because it's easier on the plant. I live in the desert and I flower in an outdoor shed, so my ladies are stressed already. And when it's 100 degrees f. in the shed, the full-strength dilution stresses them even more for a day or two. Plus...it gives me the flexibility to make little adjustments mid-week if necessary. A little calcium here...some Silica Blast there...

During the summer, I water up to 1/2 gallon or so per 3 gallon pot...daily. Were I to go with full-strength once a week, I'd be 'flushing' most of the nutes away. Or at the very least, making them settle (accumulate) in the lower regions of the pot.

Very doubtful you are seeing the effects of salt build-up. It doesn't happen overnight, but over a longer period. (at least a month or more)