I talked with a professor who also teaches meditation. We agreed that the calm and the awareness of internal states and the focus of one's attention that grow from meditation can spread to wider time periods. I have been suspicious of long periods of meditation because I think it is too easy to get off into day-dreaming and not notice it has happened.
Shorter periods are easier to stay alert to what I'm doing or not doing. The Google engineer and author Chade-Meng Tan says that good meditation can be valuably done with one conscious breath. During the day, it is easy to become conscious of just taking a breath and at the moment, drop into full awareness of self and surroundings. Pretty soon, meditative mind set is continuous. I personally don't think that means I won't benefit and enjoy a more formal 5 or 10 minutes on the edge of a chair focused on a good visual anchor.
