In my experience, I only achieve real success in learning a foreign language when I have a period of complete immersion, including the elimination of English from my life to the extent cognitively possible. That means no reading in English, no American pop music, and no fraternizing with gringos who don't share my linguistic asceticism. It can be pretty tough, especially the withdrawal from books until I'm reading comfortably in the new language, but subjectively it seems to me that every hour spent with English in my ears and on my tongue undoes a couple of hours of immersion.
However, the last time I could achieve that experience for an extended period was in my student days many years ago. The biggest culprit has been that I'm no longer alone in the world; I'm not enough of a fanatic to impose my rules on my loved ones and traveling companions. But another factor that occurs to me is that if I want to do language study related to my professional life, there's no way to escape English's domination of the Internet.
Motivated language tourists can presumably avoid cybercafes and recreational surfing, shut down their blogs and tell Mom and Dad not to expect daily e-mail updates. But if your goal is to learn a language as it is used in a professional, scholarly or business context you can't unplug yourself indefinitely. And even if you localize your OS and your browser to the target language, English's role as the online lingua franca means you'll be running into it at every click.
I used to say that the only way I'd ever properly learn Gujarati was if they'd drop me for a month in a village with the goatherds. That's fine if I want to talk like a goatherd. But if the language community I want to join is a cosmopolitan one of globalized, code-switching, and thoroughly wired professionals, maybe the monolingual immersive experience I've used in the past is no longer an option.