I have a copy of The Handbook of Mathematics, which is kind of a similar idea done commercially. It's genuinely useful, but the thing is that it's HUGE, well over 1000 pages. The main reason for this is that it is organized and fairly comprehensive, it's more of a reference than a cheat sheet. It has enough detail and depth that you can actually count on it to remind you of a subject you haven't had to use in a while.
The post here is really more like a true cheat sheet. Random topics and formulas thrown together without much organization or depth. You need to remember quite a lot already to be able to actually make use of any of this information, which to me kinda defeats the purpose. Another big problem is consistent and well-defined notation. This looks like it's copied and pasted from a lot of different sources, so you are going to have a bunch of different notational conventions that you will need to be conscious of.
The post here is really more like a true cheat sheet. Random topics and formulas thrown together without much organization or depth. You need to remember quite a lot already to be able to actually make use of any of this information, which to me kinda defeats the purpose. Another big problem is consistent and well-defined notation. This looks like it's copied and pasted from a lot of different sources, so you are going to have a bunch of different notational conventions that you will need to be conscious of.