An additional purpose of follow up in the American context is to signal to the other parties that the agreement is still of high priority. No or late follow up can be interpreted as a signal that the agreement is no longer important to the other party.
Americans place a very high value on flexibility, on the ability to respond to the needs of the market, of customers, of changing situations. Big decisions are broken down into smaller ones. Isolating individual decisions allows for rapid reaction as well as rapid revision. Up to the minute overview of agreements is essential.
Follow up is omnipresent in American life. The preference setting of email programs, social network accounts, as well as information sources can be set so that information is pushed immediately to the user.
Most doctors offices send out reminders to patients of their upcoming appointments via traditional mail, email and even voicemail. When one turns on the television five minutes prior to the show they want to watch, one sees a reminder indicating that the program they are want to watch is about to be shown. Banks offer depositors the option of immediate notification via email or text message of any changes to their balance.
Follow up is in many cases simply a reminder.