Should you study abroad for a semester or a year? This depends a lot on what you’re hoping to accomplish.
By spending a shorter semester (like a summer term) abroad, you can have a taste of the culture of your host country without experiencing most of the more distressing aspects of culture shock (homesickness, depression, etc.) because you aren’t away from your home country for long enough to get past the “honeymoon stage” of the transition. (I discussed culture shock in: https://voiceoftruth.wordpress.com/2008/07/24/overcoming-culture-shock/). However, you most likely won’t have enough time to immerse yourself in the culture or greatly improve your language skills.
If you have a lot of courses you need to complete for your major, you may want to spend less time studying abroad because many times the classes will not transfer exactly. This is especially true for those of you with double majors or those majors that would require more advanced language skills. For you, doing a single semester of study abroad may be the answer.
If you spend a year abroad you are more likely to have the opportunity to feel like a resident of rather than a tourist in your host country. Also, the more time you spend studying abroad, the more fluent you will become in the language of your host country. Your fluency, accent and vocabulary will increase exponentially in the time you study abroad. In addition, if you spend a year abroad you will have the opportunity to admire the host country in all the different season that it experiences. You can participate in all the various festivals and holidays that occur throughout the year. However, the culture shock will be greater if you spend an entire year abroad because you will become more immersed in the culture and further distanced from your own.