Moving pairs vs moving stockers

For the past few months, moving the 600 pairs every day (or twice a day) has involved a brief run through the group to check for sickness, calling the cattle, opening the gate and then rounding up all of the stragglers and calves that did not call through. The process generally takes several hours and many times, getting all of the cattle to move to the next paddock is sometimes simply impossible. Compare this to last year when moving the 800 head of stockers took 10 minutes and most of the time could be completed in less than 5 minutes...I NEVER had a stocker animal that would not immediately move to the next paddock. Even the very sick and lame ones would move, trailing the main group (making them easy to spot and treat) but never failing to move. I am hoping that as the calves get a little older, moving them becomes easier. For now, we routinely spend an hour or more rounding up stragglers with the four wheeler, pushing them to the next paddock. It's been very frustrating and time consuming.