Those LEDs flicker alternatively I believe

For awhile I removed those 2 sticks and screwed them onto another exit sign I had which had perfect mounting holes that fit perfectly...but I took them out and put it back in the original item, just....for you! hehehehe

They do flicker a bit, but it's less noticeable than most LED Xmas lights LOL! You need to be pretty close to the exit sign to see the flickering.

you can make flash patterns with this thing and the camera.....make the camera long exposure in a dark room....(I would say maybe 5 second exposure or so) then cover your lens with your hand...and shoot the shutter button and quickly swing the camera across the exit sign uncovering your hand and covering it very quickly....wait until "picture taken before uncovering the lens" and see the results on the pic!

Flickering is less noticable because it alternates taking turn (half flickers for the first half of each hz and the other half of the LEDs flicker for the last half of each hz) so that way for every cycles, the brightness stays the same....makes sense?

Hmm most of the LED exit signs I've seen have the LEDs arranged lengthwise along the bottom.

Yep I have seen those too.....