This summary is not the rule. The rule text controls.
If a grand jury is meeting in a county, that doesn't stop prosecutors from charging other crimes through different methods. Prosecutors can still file a complaint or information to bring charges, even while a grand jury is actively working on other cases in that same county.
This means the grand jury process and regular criminal charging process can happen at the same time. One doesn't block the other. Prosecutors have the freedom to choose whichever method fits the case they're working on, without waiting for the grand jury to finish its business first.
