In Germany follow-up is infrequent. Once an agreement has been made neither party feels the need to contact the other in order to inquire about the status or priority of that agreement. Agreed is agreed.
And agreements are meant to be held. The priority of an agreement remains at the level it was assigned when entered into. There should be no need to verify or reinforce the importance of an agreement.
In the American context, because people enter into many agreements and on a constant basis, follow-up is essential. It is how Americans maintain a common understanding of the status and priority of any given agreement. In many cases, parties to an agreement arrange predetermined times to communicate with each other. In other words, they schedule their follow-up.