That four hours comes from most places say 4 hours is what they want per day for a room comp based on whatever there average bet norm is for rooms- adt is really something totally different and the time play is completely subjective from the host - those are just the basics - who dat- you have my number call me if you need a better explanation
The whole ADT thing is considered kind of holy in the casino world. Unbelievable.
Take player A that plays one day a week and has an ADT of $3000
Take player B that plays three days a week with an ADT of $2000.
Clearly player B is more valuable to the casino than player A, however if there is a busy day and minimum requirement for a room will be put at ADT $2500, then player A will be given a room and player B not.
The important thing I can strongly suggest, is to never play the typical "I had just 5 minutes left" on the last day of departure, as these will lower your ADT dramatically.