For a gigabit wan pipe:
8 packets * 8 bits/packet * 1500 bytes / (1e9 bits/s) = 100 microseconds so your suggestion overflows router buffers within the first 100 microseconds. Most likely you want a minimum of 10 times that value and more likely 50-100 times that value, which is in fact close to the 1000 packets default value. However, downstream, at a 20 mbit wifi connection between an AP and a mobile phone perhaps, the same 1000 packets will take:
1000*8 bits/packet * 1500 bytes / (20e6 bits/s) = 600 ms to empty
which just goes to show that for VOIP you really need end to end quality of service, starting by tagging DSCP on your router, shaping both directions of the router flow, then honoring that DSCP in your switches, and having an AP that takes advantage of the DSCP marks to set the WMM queues. There's really no other way, traffic shaping is an integral part of a modern network.