I have something like a 20 second time limit on reports but that how it's been for a long time. It actually is an annoyance to me when someone goes on a crossposting spree. I try to multitask while I'm waiting for the timeout but then get distracted and forget about reporting the other instances. However, I understand why something like this might be necessary since with no limit a malicious person could cause hassle for the moderators by submitting a ton of invalid reports.