How Can We Combine Salah?
In all ibada rituals the principle is to move down to the closest secondary form (e.g. combining prayers) when there’s usr (hardship). A general ruling can’t be made because the situation with one person may justifiably be a hardship, while with another it might be mere inconvenience. Therefore, the final decision on whether or not a particular situation can be justified as hardship rests with the individual.