I recently saw this post, where the comments say that a substitute is required when not abstaining from meat every Friday:
https://www.reddit.com/r/Catholicism/s/xAmZLIlk01
I thought I was falsely remembering figuring out that it can be skipped without a substitute, then I found this, which reveals my memory is correct:
https://www.catholic.com/magazine/print-edition/is-friday-penance-required
It seemed debatable to me, so I searched for links to the article on r/catholicism and found this:
https://www.reddit.com/r/Catholicism/s/OTaMhW5zuu
The part saying “it’s demanded of you and we are obligated to obey” seems to indicate that the commenter didn’t completely read the article, but this part convinced me:
You see in our society, we face many sins. We do what feels good and the world encourages us to do whatever feels good. Porn, over indulging, all sorts of things.
When we deny ourselves things we eat, we grow stronger at saying no to sin. This is why fasting is such a good practice.
If we can say no to things we need, then we can say no to things we don’t need.
Sin that I can grow stronger at saying no to includes cowardice. That’s the most exciting part for me.
Instead of abstaining from meat, I will stop using Reddit and Lemmy on Fridays. I will probaly sacrifice more in the future.
I’ve had a priest suggest it to me as a good penitential practice in the past, but outside r/Catholicism I’ve never heard of it being required. Keepini mind that r/Catholicism tends to self-select for really “hardcore” for lack of a better term and very trad Catholics so it could be a trad thing. That said there’s nothing wrong with it, so if you think it will help you spiritually, go for it.