WK teaches the readings れつ and れ for the kanji 列 (“Let’s (れつ) Ray! (れ).”)
My question is: is the れ reading important enough to be taught at all?
My (admittedly limited) searches have found only a couple of ateji in which it’s read as れ.
虎列剌 Cholera
列寧 Lenin 
So I thought I’d check with the more experienced folk here before bothering the WK team about it.
Sometimes it seems like they just take info from JMdict,etc (the free database that Jisho and other E-J dictionaries often use) without checking if it’s accurate or worth including or not.
I don’t think it’s even valid for 列寧
I would just email them about it.
On top of that, it’s a confusing mnemonic. They use ‘ray’ to help you remember the れい reading elsewhere, including 例, which is partly composed of this kanji, so I am always getting 列 wrong through writing れい. If it’s not even a particularly important reading, getting rid of this part altogether would make things much less confusing.
例 is more “complex” than 列 so to balance, their readings are the opposite. れい is more “simple” than れつ so the former goes to 例.
That’s how I did it to distinguish them 
Not sure if it helps 
That is indeed a good way 
It’s less that I struggle to distinguish them and more that it took me a while even to realise why I kept getting 列 wrong, because I just associate ‘ray’ with れい and had the mnemonic stuck in my head. Now that I’ve realised, I just stick to れつ, but this is a good way of remembering the other reading, so thanks