For the US you sometimes might get a visa that's valid only for a year, and in some extreme cases I've seen people receive visas for 30 days surrounding a specific event they were traveling for .
From what I gather it mostly depends on how the person reviewing your application thinks it's likely you might break your visa terms (stay longer than you should, work when you're not allowed to). Usually happens for younger people or people involved with problematic industries (military etc)
I guess the 30 Days visa are J visa ?
I was under the impression that 5 years was the norm, considering a lot of undergrad courses (in engineering especially) take about that long to complete.
Grad schools too can take that long if you're aiming for a PhD.
(Although, when you graduate your F1 expires even if there's still time left on it; so you can't continue staying in the US after graduating without obtaining an OPT, or a different type of visa, PR or whatever).