Here and there on the Internet you can find blog posts by language enthusiasts on the topic of learning more than one language at a time. Most are cautionary. Many discourage the practice. I haven’t found anyone that has the same attitude as me.
Which is that I’d be quite prepared to dabble in ten or more languages at once.
Now, that might not be very efficient. I would probably not progress as quickly. But here’s the proof of the pudding: it would in no way stress me out. That’s the telling difference between my method and that of ‘Norm’.