I won't offer an opinion on whether to do frequent/small vs. infrequent/large changes. I would like to make the point, however, that changing 10 gallons a day is not the same as changing 70 gallons a week.
Somewhere I have a spreadsheet I built that does more accurate calculations, but for a simple example:
Assume a 100 gallon system that generates 10 "units" of bad stuff a day.
After a week (with no water changes) the tank would have accumulated 70 "units" of bad stuff. If you did a 70 gallon water change (70%) at that point you would remove 49 units, leaving 21 units now diluted.
At the end of the next week it would have generated another 70 units (for a total of 91) but another 70% water change would leave a little more than 27 units to start the third week. The point is that whatever that bad stuff is (and whatever units you use to measure it) the concentration will build up even though you are doing regular huge water changes.
Okay, what about the other approach of changing 10 gallons per day? The first day you'd generate 10 units and remove one, leaving 9. The second day the tank generates 10 and you remove 1.9, leaving 17.1. The third day would end with 24.4 units; the fourth with 34.1; the fifth with 39.9; the sixth with 45 and the seventh 49.5.
Net, both approaches will accumulate whatever waste is being produced (the same math also works for the calcium or trace minerals being consumed/replaced unless additional supplementation is done). The big weekly changes, however, will accumulate much more slowly than the small daily changes.
Extending this model out over a longer period of time increases the effect.
The challenge, then, is to make your water changes most effective (larger but less frequent) but not to delay them so long as to induce dramatic chemistry changes/shock (at or close to 100% change).
How long that is depends upon your tank, its occupants, your feeding, etc.--your "units"--but the graph inevitably looks the same. I'd suggest that, for most of our tanks, daily is too frequent to be effective and that quarterly is too long. Somewhere in between is lkely to be optimal.
(Of course, the other alternative of doing larger changes more frequently is great if you aren't constrained by the cost. Fifty gallons per day would keep everything nicely stable...except your checkbook.)