When does the traveler combine and shorten the prayer? Is shortening a dispensation or the default ruling?

The Shaykh : After this, some of the legal rulings that it is good to be reminded of follow. Among them is that if they are travelers and stop at a place where the first prayer, the midday prayer, catches up with them, the recommended practice is to combine the midday and afternoon prayers by advancing them in this situation. However, if they are on their way at the time of the midday prayer, they should not intentionally stop, but rather continue their journey until the afternoon prayer catches up with them. At that point, they all stop together, and he prays the midday and afternoon prayers with them by delaying them.