As a feller new to beekeeping I have found the screened bottom boards to be a very useful inspection tool for several reasons... First I will say I am in Arizona in the central Sonoran Desert and do not use the SBB for ventilation purposes keeping it closed all the time and though our daytime temps reach 117 commonly in June and early July before the dew point rises during Monsoon season I see no "hot bee" issues as yet. Though I did take care in hive placement with advise from a long time AZ beekeeper to use Mesquite trees for dappled afternoon sun which help allot here as direct sun can be brutal.
So where am I going with this? Well I have learned to "read" the material that falls from the colony as they go about their day to day business and can see evidence of trouble from parasites and pests as well as bits of capping wax, comb building white wax bits, and other debris including feces from wax worms etc., on the bottom slide out tray. Also I have learned the wax worms being hassled by the bees will try to develop in the space under the screen which aid me in helping the bees manage them since I destroy them when checking the tray a couple times a week.
Also if I do this check early in the morning as the sun is rising I can look from below into the bottom brood chamber for a sneak peek and observe what the bees are up to without bothering them in any way since the light is bright through the entrance opening. My hive stands are 14 inches tall and either by bending down or using a mirror (new trick) I can watch activity and see if all looks normal as well as see halfway up frames to look for brood and comb building among other things.
Just sharing this with the rest of you new folks here and it sure beats looking into the hive and disturbing the bees as new beekeepers often do not being able to stand not knowing in those first weeks and months. Yes I of course still do my inspections for a good look, but only 2 times a month now. I just find this devise a cool tool and yes it does offer venting options as well though I am not convinced that option is useful as yet and have read often of bees jumping ship for that reason.....
Anyway just a new beekeeper observation