On a typical day, I listen to Raidió na Gaeltachta in the morning, and Radio nan Gaidheal and Radio Cymru in the afternoon. Of the languages spoken on these radio stations – Irish, Scottish Gaelic and Welsh respectively, I understand Welsh the best, and the other two quite well, though my Irish is stronger than my Scottish Gaelic. I find that after struggling to understand the two Gaelics, Welsh seems much easier.
Similarly if I listen to Cantonese or Taiwanese, and then Mandarin, the Mandarin seems so much easier. My strongest Sinitic language is Mandarin, followed by Taiwanese then Cantonese. Although I don’t understand much Taiwanese, I’m much more familiar with it than with Cantonese as I’ve spent a lot longer in Taiwan than in Hong Kong or other Cantonese-speaking areas.
Among my Romance languages, French is my strongest, followed by Spanish, Portuguese and Italian. Spanish becomes much easier to follow if I’ve been listening to Portuguese or Italian first.
This phenomenon applies not just to languages – after trying to juggle six or seven balls, juggling five or fewer seems like a piece of cake in comparison, and relatively simple skating moves seem much easier after attempting more complex ones.