Although taking about stool is socially a faux-pas and tends to be taboo, it is actually a very important health topic. Feces, stool, poo, number-two... whatever you want to call it, it is important and needs to be discussed from time-to-time! A lot can be learned about the health of a patient from their bowels and their regularity. If you've ever seen a naturopathic doctor, they've likely asked you about your stool. Doctors will ask about the color, odor, shape, texture, float-ability, etc. These questions aren't being asked just to embarrass you; the characteristics of your stool can help the doctor understand how your digestion tract is running.
The regularity of bowel movements varies person to person; however in general, 2-3 movements a day is the healthiest, whereas 2-3 bowel movements a week is very constipated. Why it is important to go, when you 'gotta go: When stool is not passed and remains in the rectum, the body takes the opportunity to absorb more water, making the stool more compact and increasing the likelihood of future constipation. Also, as stool contains wastes and toxins, it is best to have these unhealthy components leave the body sooner rather than later!
Why routine is good: The body gets used to a particular environment, time of day, routine, etc. and uses this to regulate its bowel movements. Most people's bowel movements fall into some sort of routine occurring at a specific time and place (e.g. in the morning, after coffee, after work). On the other hand, too much routine can be bad for bowels. A bashful bowel is one that will only go when it is in a specific environment. For instance, you are able to go every day at home, but when you go on vacation, you bowel movements don't come as often or as easily. The bottom line is that some people just can't have a bowel movement when they are out of their comfort zone.
If you aren't too grossed out, please come back tomorrow as I promise to discuss something much more tasteful :)