I use Shimano chains with the quick links and I believe they recommend to not reuse them. Do they literally mean not to reuse them? As in if you take your chain off to clean it you have to use a new quick link? Or do they mean that when the chain wears out to not reuse the quick link?

I interpret "do not reuse" as "discard along with the chain it is used with".

They do mean ONLY use once, when it has been opened it does get a little looser and they recommend a new one everytime. That being said I work at a bike shop and I use mine multiple times. just make sure when you reinstall it that there Is resitance and it snaps in place if it is worn and clicks to easy it could come loose when riding.

Do yourself a favor and get a Connex link...or better yet get a Connex chain which also comes with the Connex link. No tools and re-use to your hearts content.

Depends. Some of them recommend one use some life of the chain. I've never had an issue reusing SRAM 8-9-10s for the life of the chain

These 11 speed links are claimed to be reusable.https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

I would not buy any off-brand quick link. I prefer to use connex links, but 12 speed is not available yet. In the mean time I can use KMC or SRAM links. I'll reinstall a few times, but probably no more than 3-4. I just read about a link failure from a person who reinstalled one 7 times.

I have reused them multiple times, in 9-10 speed applications. When they begin to open or close too easily, I discard them.

They are only around $5.00 each why risk it? Sure if you don't have a new one and its urgent, re-use until you get a chance to replace.