This is what I tried for a couple months before going on a trip this past summer. Problem is that if you don’t try using it outside of Rosetta Stone, it becomes difficult to retain. All in all, if you know someone that knows enough of whatever language to be able to converse with, it’s great reinforcement.
I tried picking up a bit of Italian and a German- well, suffice to say that in Italy, there are some places that people will just plain ignore you - I can’t exactly argue with them - how many times have you been approached by someone in the US that doesn’t speak English? Sucks, but think of it as you appear ignorant coming to a country and not knowing at least a bare minimum of their (native) language.
At least try, and they’ll work with you. Appear to be ignorant and, well, you’ll look ignorant.