I have only experienced 'Sudden Death' once. I had a batch of xtol that was just over a year old. I used a working 1ltr bottle and kept the rest in a tightly sealed 4ltr bottle. When it came time to use the last ltr, I did a strip test and it passed. I then processed a roll and it came out blank. That was about as sudden as you can get.
Originally Posted by Brandon D.
Then I used dilute (1:2) quantities and with drum processing only 150ml per roll (one shot). For the cost, it wasn't worth stretching it out that long and introducing a failure. I now use it replenished, which consumes more total xtol. It does give me the same dev times and I use 5ltr in about 6 months.
Note that the 'Sudden Death' is just that. The grain mentioned in this thread can not happen from this. XTol is kinda digital, good and then not and no in between. I would suspect the freshness of the film / exposure, before anything else.