I've been working for some time on a universe in which there is limited FTL consisting of short (up to five light years at a time) jumps between points in space. The jumps take no time at all for those on the ships making the transit but journey length as measured by universal clock (kept using the pulse pattern of a non-repeating pulsar) is, on average, roughly quarter of the time light takes to make the trip but varies considerably with some ships arriving years or even decades later than the average transit time would suggest.
What I'm trying to work out is whether manufacturing facilities could rely on imported raw material under these conditions. I've considered that a "grace-loading" system might be used wherein individual shipments are largely than the shipment schedule absolutely requires if everything arrives on time but I can't work out if that's realistic.
So my question is two fold, can an industry that relies on imported materials function when it doesn't know when the next shipment is coming provided it can assume that it will? And secondly is my method of overstocking shipments a sufficient measure in-and-of itself to allow smooth operation?
For the sake of simplicity lets assume that the raw material in question is processed elemental metals with no shelf life. Average variance from schedule is on the order of no more than a couple of months on an annual run. Smooth operation can obviously always be disrupted by a missing shipment or an excessive delay. The systems receiving shipments either have no in-system mining options for whatever reason, (generally because they don't yet have the population base), or such industry is insufficient to support the needs of the in-system manufacturing required to get local space industry going. Their industry requires the most basic raw materials to get started, planetary mining helps but getting that material into orbit is prohibitively expensive of time and energy. There is a minimum import/export cargo size but no maximum, the bigger shipments are more economical for all parties, so while they could "beat the spread" by using multiple small shipments it would be ruinously expensive.