Since my time is very limited, the most success I have had with learning languages has been with the Babbel app; its focus on small lessons (around 5-7 minutes) works well for me. However, there will eventually come a time when I outgrow Babbel, since many of its courses (Russian in particular) only cover upper-beginner and lower-intermediate study of the language. I don't know anyone else who is studying the same languages, and I don't live in an area with appropriate native speakers.
So, at intermediate and advanced levels of language study, how can I effectively learn a language in small chunks of time, without the opportunity to converse with native speakers regularly?