In anime watching communities, it is common for many people to adopt what I consider to be relatively negative habits: the “four episode test” (and some variations) and watching a show to completion despite it already performing below expectations.

I really resonate with How to Recognize a Terrible Anime (in just one episode) from Trixie (nee. Digibro), and I recommend and endorse the following set of ground rules:

1. I do not continue watching a show that doesn't interest me in the first episode or two, i.e., I do not “give an anime 4 episodes” (1/3 of its runtime, for a 12 episode anime) to “get good”.
2. I do not continue watching a show simply because I'm halfway through, 3/4 of the way through, etc. unless I'm interested in the show. Many people suffer from the sunk cost fallacy when it comes to anime. I do not. My time is more valuable than a trashy show.
   1. There are still reasons to watch trashy shows, like watching with friends, “hate watching”, critique, fan service, etc. But these are all “interest” to me.
3. I look for early indicators of a show's success in the first episodes (see the above video) and I avoid things that don't have these indicators.

Generally speaking, people evaluate anime on scales of 1-10 for arbitrary reasons. I usually only complete shows 7 or higher unless there are other circumstances. When a show falls lower later, it's harder to know and I finish shows that are “almost done” if I believe they can be saved.

Don't waste your time watching junk! Watch good stuff instead!