There doesn't seem to be a discernible pattern to how often you get Miranium and credits from mining/research probes. Additionally, they seem to go at different intervals - sometimes mining will trigger, sometimes the money will trigger, and sometimes the rare materials will trigger. Is there a pattern or timer to this behavior?
It seems like Revenue ticks every 30 minutes, Miranium ticks every 45 minutes, and items tick every 15 minutes. This would explain them sometimes overlapping, and sometimes not.