[abusharif]

there is no numbers that can say what is reasonable. It all depends on setup, applications, ammount of traffic generated etc. You will NEVER get down to 0 cause your firewall will always be hammered from internet side and you cant do squat about that, unless you disable logging ofc and that is kind of a point with logs so you can see what is going on realtime and historicaly ;)

If this is about dropped traffic generated from inside of your network you can always skip logging on trash traffic like broadcast/dhcp/bootp etc. It all depends on traffic when it comes to other applications but disabling those above would clear ur log a bit and then you can start hunting down what is left and generated from your internal network.