Your experience of mixing languages for learning
I've recently joined Duolingo, specifically with a view to improving my Spanish. Language-wise, I'm able to get by in quite a few languages with varying degrees of fluency, but my grammar is often dubious at best.
I thought it was worth improving so, I'm trying to combine French and German (both more fluent than my Spanish) alongside the Spanish. My idea is that the reinforcement and switching between languages will help all of them.
That theory was fine and seemed to be working well until I tried to add Portuguese (which was pretty basic to start with) to the mix and I found that the commonality between it and Spanish meant it felt more confusing than helpful.
I wondered if others have similar experience and views of the optimal number and type of languages to learn together?
Personally I find it best to mix only after I've completed the course. That way I can keep my focus on whichever language I'm adding, but randomizing the others is fun and keeps me on my toes. I actually started a thread asking Duolingo to please allow for a randomizing feature. If you're interested, give it an upvote and comment to help it get noticed! It's gotten a lot of positive feedback already. :)
I agree that is is best to have completed one course, or at least have some experience in one language, before starting the other one. Starting them at the same time is bound to end in confusion, in my view.
Another important factor you have to consider is that you only have a limited amount of time in a day that you can spend on language learning; if you spread your focus too much over several languages, you do not get the momentum you would have normally gotten by just focusing on one language.
For that reason, my current strategy is to complete one tree, regild it for some time, and then move on. But I'm also laddering the languages, which means for me that after the Italian-from-English tree, I'm now doing the French-from-Italian tree, and hope to continue in that fashion with other languages. Thus, you are actually learning two languages at once, but with a clear difference in fluency between them.
I'm in a very similar situation, joined recently mostly to brush up the bits and pieces I already know of several languages, but were just dying away from disuse in the back of my brain. And at the moment, I've got a bit of "spare time" on the computer to fill.
One thing I've realised is how the variety of courses I've ended up taking means that I get to choose between very different ways to occupy my brain: Korean is a lot about identifying the writing, High Valyrian can't be connected to anything I already know and thus is about memorising (but at least with Latin letters ;-) ), Dutch is about remembering what I know and linking new things to my native language (German), Italian is about expanding on an actually foreign language but with already half-familiar structures... I find that when I'm tired of Italian, I can switch to Irish (yay funny new words!) and be entertained well enough to go on, and so I spend more time learning.
And I haven't added Spanish so my brain doesn't get it mixed up with Italian.
Well, In my case I am learning 14 languages.
I have a main Focus/Target language(English), which I call my priority language. That is the language I must study everyday, without exception.
And the others, I study them in this way: for example I have a gruop of these languages Arabic, Thai and Japanese, then I would study Arabic today, the next day Thai, the next day Japanese, the next day Arabic, etc.. And in order to avoid confusion, I keep them in the same level.
Unlike you, this is how I combine languages, I always translate from my priority language to the others, and viceversa. But not between them.
And this is my way to reinforce my priority language: I study the other languages from my priority language. and I study other languages through reverse courses. In that case I am learning my priority language.
And that is my poing of view. I thing you have an optimal number of languages. So in my experience the more languages you add, the slower you will learn them.
By the way, currently I want to improve in the expressive aspect of my priority language. So to do so, I apply this philosophy to my native language and my priority language. This is: "All that you can say in Spanish, you have to know how to say it in English". This means studying idioms and slang.
That's interesting Hxvan, could you speak them before, or are you using Duolingo all the way? I have a theory that ability to speak languages is helped by exposure to a second language in early years. Then, the brain develops the ability to translate your thoughts into a language as needed. In my reckoning you can say you can speak a language at that point where you can speak that language without translating through your native tongue.
So, as I'm learning I somehow switch modes with any luck into the language on screen. In this theory the work in the different languages keeps the "jump" open and at least so far, French/German/Spanish seem to keep themselves in separate boxes. My most common mistake is to type the word in wrong language between English and the language I'm learning - eg typing in English when the question is to type the audio in German. Oddly, I tend not to get the wrong learning language. (in direct contrast to when I am tired and have travelled through a number of countries or in a new country, when what comes out is completely random)
FTR, the languages I speak conversationally with any degree of fluency are English (native), French, German, Spanish, Hebrew, Less fluency possibly down to pathetic: Mandarin, Georgian, Also ran:Portuguese, Russian, Arabic, Italian
I don't have the time to devote to one language unless I block other activities around it, let alone two. So I could never really do what you're doing. But as it is, learning two or three at a time like that can be dangerous if they have similar-but-not-the-same grammar/vocab etc in case you mix them up. I might wait on adding Portuguese, or spend a few days exclusively on it to get a somewhat more solid foundation before adding it in with the others...
I prefer not to study two languages at the same time, and that's because it would take me even more time/effort in order to do it. You could technically say that I learn English alongside with my main study language, which is Russian, but since I'm already fluent I don't even count it as actually learning.
I think using Duolingo is helping me switch faster between French and Spanish, both of which I took in school at various points. If I hadn't had any language training before or needed one for a job, I'd agree in getting grounded in only one first. I specifically started using Duolingo in both because my mind would always flash up the opposite language when I wanted to use it in conversation. So I'd be stuck with remembering quite intensely my Spanish vocabulary when in France! (The French shopkeepers I met were always nice about this, because clearly the American was trying. I do like the French!)
This approach seems to be working for me right now, but if I had to plunge into a situation of using only one language, I'd make sure I had that one nailed down first.