Yes. When nothing is due in a subject, Reps falls back to study ahead and shows you everything in it. You are never locked out of your own cards.
There is also no daily cap. Every due card is shown, shuffled, across whatever you have selected. There is no new-cards-per-day limit and no review limit to raise.
The day or two before an exam, when the goal is consolidation rather than efficient scheduling. Reviewing a card early does not damage anything.
As a daily habit, it undoes the point of the schedule. A card is due when it is due because that is roughly when you were about to forget it, and answering it a week early is easy, uninformative, and a poor use of the twenty minutes.
If you have finished a session and want to keep going, adding new cards is almost always a better use of the time than re-reviewing ones that are already holding.
Having no throttle means nothing stops you from adding two hundred cards on a Sunday and meeting all of them again on Monday. The pacing decision is yours. The seven-day chart is where you find out whether you made it well.
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