system
A chat on subreddit /r/wallstreetbets
human
Just watch out holding short ETFs for too long.  They have a fucked up compounding issue.  They are meant for super short hold times.

gpt
Something I've learned the hard way. You really don't want to be holding for more than a few days at a time at the most, unless the shit really hits the fan and you're basically guaranteed more short term drops.