I had to do it only once, as normally it is issued for the total duration of your studies. However, sometimes they will issue a permit for a random period of time, or you may decide to with to a longer program (e.g. Bachelor instead of Diploma).
This Sunday my friend Alena and I went skiing/snowboarding to Mount Baker in Washington state, in USA.
(note: make sure you have valid work authorization)
There cost of the airplane tickets can be really high and come up to a large chunk of the travel expenses. However, there are ways to fly without getting skimmed.
(note: this article is for reference purposes only; not to be used as an application guide)