I personally do through status monitors at larger cloud providers at 30 sec resolutions, never noticed a downtime. They will sometimes drop ICMP though, even though the host is alive and kicking.
actually, why do people block ICMP? I remember in 1997-1998 there were some Cisco ICMP vulnerabilities and people started blocking ICMP then and mostly never stopped, and I never understood why. ICMP is so valuable for troubleshooting in certain situations.
I've rarely actually seen that advice anywhere, more so 20 years ago than now but people are still clearly getting it from circles I don't run in.