Like the emergency brake on a train, cl_flushentitypacket is good to know exists, but you should never pull it during normal operation. In the finely tuned symphony of Counter-Strike 1.6 's netcode, this command is not a soloist – it is a fire extinguisher. Keep it on the wall, and focus on your aim, your gamesense, and your rate 25000 .
If a player had their rate set too low for the server's tick rate, or if the server was configured poorly (many non-Steam or "custom" servers had inconsistent settings), the data pipeline would become clogged. This phenomenon is known as "Choke." When choke hits 100%, the client stops receiving updates, leading to a flush.
Invisible players are usually caused by a mismatch between ex_interp and the server’s sv_clienttrace . Set:
You will likely see a small hitch in gameplay. The command automatically resets to 0 after one flush in most versions, but some clients require a manual reset.