It seems to me that we do not directly experience time; that is, we cannot purely perceive it. We experience it objectively with clocks, but this is external to our individual experience of it. It is extremely hard for me to judge the duration of time without some sort of reference. For example, it is impossible to describe how long an hour is. It seems to me our subjective perception of time cannot be based on time, but rather is solely based on what we are doing and its relation to time.
Time is a complex subject, but hopefully this makes some kind of sense.