JMHO, after 40 years of racing and chasing, but anything down before the gates open to everyone should be removed ... period ... once the gates open, its fair game and mark off what you want, but if you are found to mark off double, or the seats in front of you to 'control' your leg room, etc .. security should make a quick round and ask you to remove your 'excess' prior to the first event ...

... also, seats should be cleared prior to ticket gates opening on EACH day of multi-day events ... again, JMHO