Even if mIRC would /who all chans say every 5mins - and I assume it never will, as the slight gain in "useful once in a while" funcionality can in no way justify the additional
constant load for all IRC networks - there will always be some situation (or user) that - allegedly - requires a more up-to-date /who-result.
Also note that various IRCd take various parameters for the /who command, so replies to custom /who-requests could complicate attempts to get a reliable "full poll" if mIRC would not opt to ignore
all custom replies at the cost of even more overhead.
Also bear in mind that while the notify list provides a definite result - a user is or ain't online - H/G has little informative value. There will always be plenty of users away yet not set away, and some users marked away while conducting jolly conversations.
