I actually work the chains for high school games and can lend a little insight on this.
The sticks are suppose to be 2 yards or more off the sideline. But the old rule of chains being set before play resumes went by by with the HUNH offenses. Only the box(the down marker) that marks the line of scrimmage has to be there. There is no way the chains can keep up. The offenses go too fast, the chain gang fights thru a sea of humanity of players, coaches, camera men, ball boys and boosters, so it makes hard when you are tryin to get by with poles attached by a chain.
Lastly if there is a play coming to you you are supposed to lay them down or take them with you out of the way. There is a clip marker on the chain so they can put them right back where they were every time.
The chains are for the officials mainly, the players need to look at the line of scrimmage before each series and get an idea where the first down is.. It their responsibility