Translation of ab und zu

Let me explain: A company that has may difficulties needs to change its behavior, its organization, its business plan and sometimes the entire management. In this case, change must happen anyway.
Seldom only do such incidents occur, thank God, but the fact is that these incidents, which are started by a relatively small group, need to have a broader support among others in order to exist.
On the second day we visited the Perito Moreno glacier by foot. It is one of the most beautiful glacier in South America and certainly the most visited, as it can be reached easily by car.