Time is a fundamental component, and it is often associated with the budget.
If the time is short, only a week available, it is better to leave for nearby or easy destinations. By easy I mean those places where you can navigate directly in front of the hotel or where the movements are easier: no boats, planes, complicated transport on site, etc. . Losing one or more days on site can be compromising. Moreover, leaving for a week means, for most people, excluding all those destinations far away where it takes one or more days of flying, and tickets above 700-1,000€.
If you have more than two weeks you will certainly have more freedom to move around on site (less anxiety of losing a day of activity) and the certitude of recovering an expensive ticket. On the contrary, you have to keep in mind that a longer stay means a higher expense, so the longer the journey, the less expensive the destination has to be.