I've stopped looking for "reasons" that I don't see anything YEARS ago!!!!!
Deer are wild animals,not cows coming back to the barn at milking time. They are creatures of habit,but the bottom line is that they do what they want when they want. Can you pattern a deer??? Why YES!!! Actualy you can..... But,Can you "time" a deer??? The answer is simply, NO!!! Weather,barometer,activity,(both human and animal) MANY factors affect deer movement. A sharp drop in the barometer could make them get up and feed at noon. Then in the evening,they have no reason to get up and move. So, you do not see anything.
Pattern them them the best you can,then hunt!!!!! If you see them, GREAT!!!!! If you don't well, That's HUNTING!!!!!
GOOD LUCK!!!!!!!!!!