Reporting dead numbers

I have a question about this post What to do with dead numbers! (couldn’t reply to it as it’s closed)

when/how should I decide to flag a number as dead?
For example: I’m not in the US time zone, so I sometimes try to call em outside of their shift.

I’m using Skype and sometimes I get: the number you dialled is not in service this time (so I guess they didn’t open it up and I don’t report it) and sometimes it just disconnects after 1s w/o notification.

Just asking if marking dead numbers is still helpful (or if people here just move on to a different number and don’t care that it’s dead).
thanks