both Hilel and Shammai have it right, You need to concentrate on the words of the Shema, and do it in specific ways, with a specific posture and all that AND You also need to have Shema infuse the nature of your life, as you rise and as you lay down, as you walk on the way and as you sit in the house. So, if you have a habit of only focusing on Shema in a specific place and time, you need to build a practice to let it soak into all your life And if you habit of having shema infuse all your life, but you don't spend a specific moment in which you focus on the words and your body position, the time and the place, then you need to develop that practice of concentrated recitation as well.