Use Oldest batch first
When you ask me if I want another batch after submitting the just-finished batch of indexing, you need to give me my oldest or soonest-to-expire batch first, and add the newest batch to the end of the queue. It needs to be a FIFO (first in first out) list/queue, not a LIFO (last in first out) list.
When I come back a day or so later in the week to work more on what I had, you have thrown away my oldest batches, leaving on the newest ones, if any. You should have left me a full list, based on the way I work on indexing on Sundays. The batches I'm most experiences at and the most skilled at are new on Sunday but gone by Tuesday. Today, Wednesday, I can't see what I got on Monday, because you used Monday first so Sunday batches are gone.