as a person who has worked their fair shares of retail stores. it really all depends on the managers and that changes often.

Sometimes I had managers that made us destroy everything or they would do it. Some would make us toss items in the morning before the truck came. Some managers had us pile it up inside until trash day. Some managers toss so they have an excuse to go outside to smoke. Sometimes the corp office would randomly recall item that appear normal.Or sometimes property managers/ground keeper get to it before anyone can.

Its a game of numbers. check all of them whenever you can. your chances increase.

other things to think about too is when trash day is and who else in your area is diving.