Fast charging is not only the fastest, but also the most expensive charging method. That is why your employer prefers charging at home or at a public charging station. In practice, fast chargers are only used to charge the battery in a very short period time whilst on the road, allowing you to travel long distances. So use your personal charging station or a nearby public charging station as much as possible and limit fast charging to a minimum.
Note! If the charging rate of your home charging facility is higher than the average public charging rate, charge at public charging station as much as possible.