Illusion of continuity I read an article that included the following -
 "Through careful, mindful observation of this process of sensation overlaid with cognitive evaluation, it’s possible to tease apart the raw sense data from all the mental activity about it.

And when you do this, you may notice that the raw physical sensations, which until now you had always assumed to be continuous, are actually absent much of the time.

What’s happening is that raw sense data arise and pass away rapidly in little chunks, with gaps in between the passing away of one chunk and the arising of another.

Some of those gaps can be quite long, relatively speaking, but normally you don’t notice this because all that mental processing about the sense data fills them in, giving the illusion of continuity."

I have been meditating for about 6 years and attended several retreats but I still don't understand this on an experiential level. I dont think I have assumed them to be continuous.
It just seems obvious to me that sensation isn't always there. I get an itch and then it's gone. I have a pain and then it's gone etc etc. maybe I'm misunderstanding this concept?? 
Does it mean that for example an itch that lasts for 10 seconds is not continuous for the 10 second duration? And same with a pain?   Perhaps my concentration is not strong enough to ever notice this. I try to examine a sensation sometimes but an itch just seems like an itch to me.
I feel I'm not making much progress,if any at all, with this stuff. I read about what is apparently supposed to happen, things you're meant to notice and experience, insights etc but my meditation just seems to be the same thing every single time. Sitting, noticing breath, thinking, noticing breath, itch, thinking, notice breath etc. It feels more and more pointless everyday. I don't seem to be learning to see the "true nature of reality" or heading toward "enlightenment" Why not? Where am I going wrong?
What they mean, is that our experience is assembled from hints presented by the sense organs. The eyes, ears catch glimpses of what's going on, esp. as we move around - and then build a theory from those hints, theory that we see as reality. There's a lot of assuming going on during that process, a lot of interpretation, and a lot of habit.

EDIT

Once you "let go" enough, you start seeing it. By "let go" I mean the unconscious process by which we maintain our contrived world. Nowadays I see it at both micro and macro level. For example as I hold the cup and look at it I can see how the mind "grasps" the "signs" - raw momentary snapshots of some distinct features, and how it "tells" itself what these signs imply by inferring the cup from them. I see how the mind goes over these "signs" again and again in circles, telling itself the story of the cup. Similarly, at the macro level, I can see how the mind grasps the facts of the world and builds the narrative of my life from these.

When some people practice mindfulness, they practice the opposite of letting go. They think mindfulness is when your observation is watertight. But watertight observation is really just a tighter version of the assembly process by which we contrive the world. Instead, as you stop trying to be in control of experience, you start seeing the gaps in the model. These gaps is what we are after - but you can't contrive your way into them, you can't control it - it only comes from letting go, which involves handling tremendous amount of insecurity.

EDIT2

What @xxxx means with his "looking for keys" analogy: normally the way our mind works is, we get a hint from sensory organs, we build a hypothesis of what we are looking for/at, and then we validate it by examining the evidence from sensory organs. If we approach meditation with the same attitude, we would say to ourselves: hey, I must be looking for gaps in experience, gaps in the modeling process, and here is how it's supposed to look like. But you can't see the real gaps with this attitude, this would be contriving gaps with your mind, like dreaming yourself a dream. Instead, it comes from letting go of the inner dialog, of re-telling yourself the story of what you see (micro), and the story of your life (macro).