Let me give you a scenario:
5 iron outposts one is almost depleted 2 are somewhat depleted 2 are new. You would like to know the status of them but they are miles apart and if you link all chests in outposts with wire and send that wire (red or green) back to the base you will have signal all mixed up showing total of all 5 outposts not each one individually.
Solution -
Smart inserter can read logistic network status and move red wire to control chest when quantity of items goes over a threshold.
Another smart inserter removes wire from control chest when quantity drops below a threshold.
Threshold have to be set up for each pair of inserters individually.
All control chests are hooked up to decider which sends signal over the wire to the base. @ base status of the depot can be displayed however you want, below is the ststus of coal warehouse containing over 700k coal.
Display can be changed to numerical display (coloured in 0.13!!!) etc.
