Thanks Andy :)

After my first two years of French classes, I've almost always learned 2-3 languages at a time. My progress is a lot slower than when I focus on one language, but I continue to improve in all of them gradually. It can be done if that's what you want. Most people who say you should only learn one language at a time are monolinguals or bilinguals. In fact, at the point I'm at now, if I only learn one language at a time, I get rusty in all of the others, which is frustrating.