We all know of those Kingdumb Hells that don't have windows. And I never saw an a$$embly hell that had windows that would let light in that would reach the auditorium. So, what do they do if the lights go out during the middle of a boasting session?
I can see how this would be an issue. Imagine you are elderly and standing to sing a song, and in the middle of the first line, it suddenly goes pitch dark. Or, you have small children starting to wander, or you have to take them to the back (perhaps to administer their beating because they didn't sit quietly). You get just out of the row, and the lights go out. As I know, most witlesses do not carry portable flashlights or headlamps for such eventuality--I do, however, recommend anyone still attending boasting sessions to hide a small flashlight in their bag (use the lowest setting you can if the lights do go out, to egress the building).
For sure, if there are no windows, reading the LIE-ble or any publications can be pretty difficult in pitch dark (as can accessing the platform, as you could trip on the stairs if you are not prepared for sudden darkness). It is also pretty difficult for anyone in the audience to keep up with their washtowel--giving a comment in the exact words of the paragraph is difficult if you need to read the answer, and the lights go out before you can read it off. Granted it is not yet very common in the Americas or Europe, but given the situation in the Middle East and if we side with Israel and earn another oil embargo, and that the coal has been cut off for "environmental" reasons, it could well start becoming more common.
True, most of those places have battery powered emergency lights. Problem with those is, given the lousy quality most of those buildings use for their materials, they are not to be trusted. All it takes is for the battery to self-discharge, fail to charge properly in the first place, or a blown light bulb in the fixture, and they could be left in pitch dark. This is most dangerous for small children that could be trampled, or the elderly that have poor balance. But anyone can bump into a chair in the dark and get hurt. Even blind people, not themselves directly affected by its going pitch dark, could be imperiled by others who cannot see and are not used to it.
As I mentioned, most witlesses are not equipped for this situation. And it could work against them if the hounders start rounding up all available lights (they are not especially good at returning property to its rightful owner). This is why a small light that can be hidden in a pocket or bag is best, if anyone gets them. Putting it on its lowest setting is usually enough for you to get out with it, but not enough for Brother Hounder to round up for use (most of them can't figure out how to adjust the output of those things). Of course, the smartest thing for them to do is to end the boasting session when this happens--but I know as well as anyone else does that they never do the smartest thing.