I completely agree. It's not that it's not possible in English to come up with a phrase that needs an article for weekdays, it's the fact that on its own it sounds weird. The fact that you need the article in German is not enough indication that it needs to be present in the translation, as rules in each language are different. Since no context is given here, I think it should be at least accepted not to include the article.
Guys you're all leading each other astray here. There are a lot of sentences where you use articles with days of the week. It changes the meaning of the sentence or allows you to word something in a different way.
Indefinite article We met on Friday vs We met on a Friday immediate vs distant past (can also work with future) denoted by indefinite article
If the day is singular ie Friday The Friday we met was the best day of my life The article is used to refer to a specific date
If the day is plural ie Saturdays The Saturdays we spent together will always be precious to me. There's not really a non-clumsy way to express this without an article. It denotes a repeating event.
Essentially anywhere you say "the day" or "the days" you can say "the Friday" or "the Fridays" if there's some reason you want to emphasise the day of the week.
I agree. One would almost always say "I spend Saturdays and Sundays in March, ..." or "I spend every Saturday and Sunday in March", over "all the Saturdays and Sundays in March"... Perhaps, the article is a little more likely in past tense: "I spent all of the Saturdays and Sundays of March, inside" but even then a possessive seems more likely "I spent all my Saturdays and Sundays...".
Wikipedia also has some usage notes about
It fits in German as article is needed, but the English translation is wrong. One would say 'on Saturdays and Sundays, I....." but even then, its unnatural. We'd commonly say 'Every Saturday and Sunday, I...." Even saying eg The Saturdays and Sundays are good", is just cringeworthy, if mot incorrect. The same sentence this way "Saturdays and Sundays are good" has a natural tone and is how English speaking people would say it.