Sketching isn't just about drawing, it's all about 'being there'. The experience is more than merely visual. Sounds, smells, the weather, are among lots of factors which make up your experience of a place or a moment. How you feel inside yourself - happy, sad, stressed, relaxed, etc. - will all effect your memory of the experience when you try to recall it in the studio.
Taking the time to sit and sketch will not only give you a visual record but the time spent in one place even if it’s only a ten minute sketch allows the other factors an opportunity to have an impact. Taking time to sketch means staying in the same place, looking at the same thing for an extended period.
With the hectic pace of life today, taking time for passive absorption is almost unknown. When was the last time you stood still and observed any of anything around you for more than a few seconds before shifting your gaze or moving on?
In a car or a train the experience becomes similar to the sort of subliminal advertising that was banned a few years ago. The images flash into your mind almost without you being aware of them but they are implanted in your memory and are a resource to be used.