I’m not sure where people usually get builds of ntp for Windows. As I understand it, there are no Windows builds provided by ntp.org. Meinberg has an installer, which seems to be recommended on Internet.
What we are interested is the number of requests and their timing. Normally, a recent version of ntpdate should send 4 requests to each server with a 2-second spacing. In the packet captures we see that it’s sending a flood of requests for few seconds. Maybe it doesn’t do that always.
If you install wireshark and start a capture on port 123, you should see all NTP requests and responses. On command line, you can try ntpdate pool.ntp.org and see if there is not a flood in the wireshark window.