Odd regular, irregular and unknown publishing

It seems reasonable to me that a publisher would have some sort of timeline in mind when publishing a serial. I understand that there are subjects where few articles are generated and it takes a while to amass enough to publish. That should be when irregular or odd regular publishing schedules are utlilized. There are a couple of publishers who seem to take great delight, though, in publishing at such odd intervals that it makes trying to create a receipt pattern or a chronology pattern in an ILS nigh to impossible.

I once had an 8 year lag between cover chronology and actual chronology. Right now there are at least a dozen publications that are subscribed to by my library that are at least 2 years or more behind schedule. At what point does the publisher give up on back dating the cover and just deal with the year it actually is? When I received that 1992 issue back in 2000 I was befuddled. I had to hunt through old Kardex cards and through the catalog to find the record needed and then update everything. The situation became even odder when the publisher then decided to skip those intervening years and pick up with 2001 cover chronology!