This is the mistake that people are making. The goal of microloops is to start low and move upwards to your sweet spot and then work from there. Rather than trying to determine the exact breakpoint, because it inevitably fail, you should consider thinking in terms of progressive growth. No one will be recommended to stay on microloops forever. It is simply a way to manage recon and growth.
The “aim” should be optimizing results, not simply consuming the entire 15 minutes. Focus on what will give you the most benefit right now, then work from that. Sometimes that may mean going down, sometimes that may mean going up.