I went on an "add-on" night a while back, maybe 2017. The crowds were very light, as expected, but there was also a noticeably less amount of scareactors, both in scare zones and houses. I figured this would be the case as well, with the cast having prior commitments, scheduling conflicts, contracts, etc. Still a fantastic time, but keep that in mind if you go that Monday. Who knows, maybe this year it will be packed lol.