In cricket, I have often seen that incoming batsmen come in and mark the off-stump line with assistance from the non-striker. This is done by holding the bat in line with the stump till aligned, then scratching a line in the pitch with their shoes. It makes sense when done by openers, but I have often seen batsmen coming in at number 7 or 8 and performing this ritual before facing the first ball on that end of the pitch.
Why do incoming batsmen mark their line even if they come in lower down the order? Shouldn't the line marked by the previous batsmen be enough?