The decay of scent theory is not 100% proven but Alexandra Horowitz was involved in the study (I think) suggesting it has some influence on dog's ability to predict what will happen.
We have, over generations, selected dogs with the ability to scour their environment for every single cue and use that info to predict what will happen and change their behaviour based on it.
A simple example is a dog that knows you're in a bad mood and keeps out your way. You might not say or do anything but the micro expressions on your face, the hard/sharp movements of your body, the smell of you (stress hormones) etc all inform your dog. Over time he learns that particular set of circumstances is more likely to result in being shouted at and that keeping away from you reduces the chances again.
You or your house will be every so slightly different on a Thursday.
For example, four hormones are involved in excitement. It's possible that you are slightly excited on a Thursday and so have slighlty elevated levels of hormone which the dog can smell. Over time he links this smell with your dh coming home.
Maybe you tidy the house a bit during the day and he uses that bit of info.
Maybe you spend a bit longer preparing dinner = info.
Maybe you have a certain, tiny, difference to your facial expression.
Maybe you lift your head a few millimetres when you hear a noise and he learns that you doing this movement several times coincides with dh arriving home soon.
and so on.
fwiw I don't think that makes him less clever than a psychic dog; I think it makes him (and all dogs) brilliant.