Some US universities offer a master's program that lasts for just a year. At times the cost of such programs are higher than the regular 2-year MS programs.
When should students opt for a one-year master's? What are the merits involved in such an option? The demerits seem to be many: lack of time for courses or internship opportunities or learning in general, less useful for a research career, etc.
I don't think the length of program should be a direct factor when deciding on a masters program. I think you need to think about what each program gives your for your investment (time and possibly money).