[Realism]

This should be your PRIORITY.

There is no point in testing it out. Because you probably won't learn that much in 2 days by listening/watching Japanese all day long.

However, if you do it for 10 days, 20 days, 30 days....then the improvement is VAST.

I'd say try it for 30 days...and then go from there.

I've been doing it for 2 months now....and watching Japanese films/media is getting much and much easier.