If you have an unlimited ride Metro Card, you can use it as many times as you want during the month but you won't be able to swipe it back to back to prevent abuse.
Similarly, 7 queries per second is a decent limit as it allows you to send more than half a million queries (Exact number = 604800 queries) in a day.
Total number of queries for a day doesn't really matter much if your peak traffic is above a per-second usage quota. That being said, I think the quota is pretty generous.
If you have an unlimited ride Metro Card, you can use it as many times as you want during the month but you won't be able to swipe it back to back to prevent abuse.
Similarly, 7 queries per second is a decent limit as it allows you to send more than half a million queries (Exact number = 604800 queries) in a day.