If you're using RO/DI and mixing to parameters close to your tanks chemistry there should be no issue what so ever with frequent water changes.
I do not see an issue with either water change schedule.
Corals go down hill much faster than they show improvement, it take a lot of patience.
Yes, I use RO/DI (test for zero ppm before filling up my 30gl brute) and always mix to 1.026
I did hesitate to receive that info but given I am new and reefing is very different than freshwater setups, I figured it could be a possibility.
I'll keep to my weekly water changes, it just makes me feel good