Probablly to do with either g_floodprotect (set to zero), or (in cod2 at least) with the spamdelay set inside the quickmessages.gsc file. In cod2 it's set to 2 seconds, like so:
PHP Code:
}
self saveHeadIcon();
self doQuickMessage(soundalias, saytext);
wait 2;
self.spamdelay = undefined;
self restoreHeadIcon();
}