Code:
on *:notice:*:#:{
if (%notice [ $+ [ $nick ] ] > 1) { halt }
set -u5 %notice [ $+ [ $nick ] ] $true
}


This won't work. You never increment the variable and then
verify if it's greater than 1.
Also, the '#' will make the event listen only to channel notices.

This would be better imo.

Code:
On *:Notice:*:*:{
  HInc -mu60 NotIgn $nick 1
  If ($hget(NotIgn,$nick) > 1) {
    HDel NotIgn $nick
    Ignore $nick
  }
}


Regards

tropnul