I've had bees for just over a year, so I'm definitely a newbee.  I do
have a good mentor though and have done lots of homework and fieldwork.
I put slatted racks in 3 of my 12 hives.   We're in our 6th week of hot
and dry (95-100 F) after a strong spring flow.  One of my Italian hives
has been covered completely with bees at night and during the days.
This became a problem when I added 8 hives of Buckfasts that are over
fighting with my outdoor bees (they're aggressive feeders all right,
gentle to humans but rough on other bees though I'm sure the weather is
a factor).  We added the rack last week on that hive and the reduction
in bees outside is dramatic.  The other hives with racks are smaller but
it has reduced bridge comb to the bottom and gives me more room to work
with trackboards and other mineral oil treatments for the vampires.  In
this weather the ventilation sure can't hurt either.