The number of reports a chatter has depends on the room - I've seen three, four, and five in different rooms. Imagine report flags like physical flags, instead virtual ones that replenish magically after a certain period of time. You may take one of your flags and stick it in a chatter message bubble as you see fit. When you've stuck all your flags in message bubbles, you are now holding zero flags. When a mod signs in, they are able to review what flags are in which message bubbles. They can act upon the messages if they so choose (by doing nothing, deleting the message, muting the offending chatter, or kicking the offending chatter), remove the flag from the message bubble, and then hand it back to the chatter that flagged the message. So it's not a time limit where your flags regenerate so you can make more reports, rather it's a matter of a mod reviewing the message you put your flag in so that they can return that flag back to you. If there is a mod logged on while you're making the report, chances are you'll get your flag back quickly so that you can report another message. Where as if there is not a mod available for a few hours to review reports, it will take longer for you to be able to flag another message.