When you are out and about totally absorbed in your photography, being behind the camera, time slips by unnoticed. It is a very strange thing.
You are totally engrossed, completely focused on your art, meaning there in no space in your head for any thing else but your photography. You are absorbed in the process, looking for subjects to photograph, visualising what you are trying to create, framing your compositions, making your pictures.
It is not that time stands still, no indeed, it is simply that time disappears completely. You vanish into p-space and at some point later, unwittingly, you reappear once more your photography experience complete. Several hours may well have passed, you are simply unaware of them.
In the mean time, if you are lucky and indeed have been on form that day, a few 'keeper' images may have been created. But even if they were not, you will have had the zen-like experience of timeslipping and put a big smile on your face into the bargain.