That's because you're not setting up alerts to warn you when your buffers are depleting. In a simple system like Factorio, adding a buffer to catch oversupply s

That's because you're not setting up alerts to warn you when your buffers are depleting. In a simple system like Factorio, adding a buffer to catch oversupply should never stop production more than not having a buffer at all. (A related problem in Factorio is that the available buffers tend to fill themselves based on the topology of the belt network rather than actual oversupply, and then tend to not empty into where they are needed until the logistics network is developed. In the real world there are price signals and communication between factories, so supplies are not allocated to factories on a first-come first-serve basis (inserters serving themselves).