I usually try not to approve posts out of order within the same thread for that reason. But, I will sometimes skip over long posts in one thread and mod the later posts in other threads.
In terms of my own posts, I often write responses to threads as I am reading them, but there are still many posts to approve in the thread that I don’t have time for. In that case I usually try to mark my post as “un-modded” so that it won’t come up until anoyher mod (or myself) approves it, which will hopefully be after the previous ones.