In our association, wings count how many on the line. We do this by counting the number of players on the line, starting with the guard our side of the center and working our way outside. Since the center is always on the line (in theory), then it is not necessary to count him. Then, having done this, the wings signal to each other how many they have on their side on the line. Hand to the thigh - 2 on the line; hand across the belt buckle - 3 on the line; hand across to the chest (place just above heart) - 4 or more. For example: Linesman has guard, tackle, tight end on his side, with the wide out in the backfield, then he would signal hand across the belt buckle with the arm on offense side extended out (to signal wide out in backfield).
Lines judge has same players positioned as linesman. His signal would be the same also. Now both linesman and lines judge know they have 7 on the line (their 6 plus the snapper). We also signal each other with a closed fist to let each other know that we got their signal. If one of us gets a brain fart and forgets to signal number of players, the other one will still throw a flag, then we come in and ask each other how many we had on our side.

This has made it very easy for us. Plus, the downfield officials can always look at us to see if we are signalling wideouts in the backfield to see if the inside player is covered or not.