I'll assume you are measuring the "play" at the rim? 2-5mm sounds
excessive. Your brakes will need to be a long way from the rim to
stop brake rub.
The play is common to cartridge bearing style hubs. I probably get
under 1mm from my Mavic hubs. It's just noticeable shaking the top of
the rim side to side.
Too tight and you introduce angular contact as you get from a cup &
cone assy.
If the bearing is utterly stuffed, the play may be difficult to reduce
to an acceptable level without increased friction. Buy new bearings,
but don't be sucked in to wasting money on ceramic testicles, unless
you have money to burn and a burning desire be half a micron per
megasecond faster.
JS.