"We all know that Flash moves so fast that time slows down, so to others it looks like he is running at superhuman speeds(because he is)."
This isn't the case - you're better describing the "speed" powers of Zoom, AKA Hunter Zolomon. He plays with time so he can move quickly, as well as in other ways. The Flash (almost all of them) just runs way hella-fast. Flash has heightened perception (it's been described as "speed-geared vision") so he can actually see things at those impossible speeds - otherwise it'd be a chaotic blur to him, just as he is when others see him.
Mike Baron wrote another good example of "Flash-view" in a early issue of his run. Wally is in a theater and suddenly switches to super speed instinctually. He notices the movie "stops" - it hasn't, he's just moving so fast he's between the frames. He realizes the reason he kicked into speed - there's a bullet tickling the back of his neck, about to pierce his spine. So at top speed (which at this point in Wally's career is "only" about the speed of sound) he combs through the theater, grabbing other bullets from the air and catching the nut in the back of the theater who is shooting them. And though it all takes place in the fraction of a second, he's viewing it in time relative to him, and he perceives it as several seconds, up to a minute. This is because he's concentrating carefully, working in detail.
In Baron's first issue of the book, Wally must run cross-country to deliver a transplant heart. He does it in (IIRC) under a couple hours - faster than any jet, but far slower than Barry could run (see previous comment about Wally's slower speed). He perceived the trip as only that couple of hours, and not however long it would take a human to run that distance.
So yes, he CAN "zone out" (much like you would on a car trip), but can also be in the moment, giving that "time slows down" perception, but not a literal time dilation effect.