In systems with zero or very low Nitrate, with alk and calcium readings as desired, I personally change 10% every other week. I consider this to be for trace element and minor buffering ion replacement. On off weekends I buffer with Kent Marine Super Buffer DKH. I dose Kent Marine Liquid Calcium as needed, which is daily in my reef.
If I ever obtain a low alkalinity and high calcium, i immediately do a 20% change, scheduled or not... theory being to replace borate and magnesium.
This has been my technique for a decade or longer in marine aquarium keeping, with almost no deviance in this method or product used. In theory, provided alkalinity and calcium were both in the acceptable range, I could begin dosing B-ionic, rather than using 2 separate additives. But I figure why change what works?
You asked an intersting question without actually asking it. Which is this... is it better to do a 1% water change daily or a 7% water change weekly? Eric Borneman has an article on this topic. He studied in great depth the impact of such differences on Nitrate and other important tests. The bottom line.... there isn't much difference at all. If you want to use a continuous water change system for daily water changes, go for it. If you want to do a weekly 7% water change, do it. Mathmatically, the difference is minimal long term. VERY minimal.
I personally like small changes to the environment. My reef gets a 4 gallon water change every other weekend. But I actually change 1 gallon at a time, over 4 separate water changes, spread out over the weekend. I think it causes less stress on the fish.