What is the smallest interval for the watch command?
The man page and Google searches do not indicate what the smallest interval lower limit is. I found through experimentation it can be smaller than 1 second.
To test, I ran this command run on a firewall:
watch -n 0.1 cat /sys/class/net/eth1/statistics/rx_bytes
It clearly updates faster than one second, but it is not clear if it is really doing 100ms updates.