I couldn't edit my post no more..
Seems like there is no documentation about this setting in the help file.
/fupdate is more or less still a work in progress
Also seems like the way it works, has been changed several times over the years.
this feature once was an option in alt + o, then it got removed and the option was made permanent, then it was revisited with the above thread and the behavior was changed twice during a beta phase, to be what it is now but there haven't been many feedback about it, which is most likely why there's no documentation about it yet.
Does MiRC set fupfate to a default setting each time it starts?
Yes, it is set to the default value 0 when mIRC starts.
Is fupdate always enabled, and does it get adjusted automatically up an down?
Yes, it's always enabled. Its behavior is such that internally, there are adjustment made which will make the behavior as though you were executing /fupdate N with N going up and down as you said, but in reality your /fupdate setting never change (you can check $fupdate).
