The American Heart Association recommends that, unless you have a known cardiovascular problem, it is sufficient to have your blood pressure checked every two to three years. Everyone experiences periodic fluctuations to their blood pressure depending on activity level, stress, etc. But people with sustained uncontrolled high blood pressure run a much greater risk of developing cardiovascular disease. Ironically, some people only suffer from high blood pressure when they have it checked by a doctor or nurse. This is also why prudent doctors will not prescribe a drug for high blood pressure unless the patient has shown consistent high blood pressure over a period of time, or only after conservative measures such as stress management have failed.
Most people can manage their blood pressure adequately with lifestyle choices.
People with a tendency toward high blood pressure would do well to eliminate caffeine from their diet. For a small percentage of people there is a correlation between excessive sodium intake and high blood pressure, but for most people this is not as important as was once thought. Get enough of the right kind of exercise. Learn stress management techniques if you are a Type A personality. Try to maintain a healthy weight.