@CissyT Any answer you get from anyone who doesn't have access to actual company information would be a guess.
I just had an order arrive five days from the time I placed it. Again, no idea why it came a solid week before the estimate I got when I placed the order! I always check out carefully and slowly so I can cancel if I don't like what I see. I've been lucky though - all deliveries on or like the most recwnt before any date promised.
BTW, if I were to guess why some are slow - there are more jobs available than there are people to fill those jobs.