I feel your pain on this. I use a bulk ink system on a mutoh 1604. From day one I made it compulsory to keep 2 bottles of spare ink of every colour.
We have to insert these chips into our bulk system. The day before install everything was printing ok and one of the chips ran out. No problems I inserted the other chip, didn't work. So I resorted to using my emergency chip, it ran out and the job still didn't get printed on time.
Ink up, and chip up to the max at all times, you never know what emergency job is round the corner.