[Links at bottom]
"I feel I must learn every single scale, chord, and arpeggio by next month or I will go straight to Hell"
This is really only a simple suggestion for self-taught pianists who believe it is important to master "basic technique" (that is, all the conventional scales, chords, and arpeggios that everyone from Beethoven to Tatum would insist on) but who cannot, for whatever reason, have a proper teacher.
Perhaps you've been plugging away at as many scales and arpeggios as possible for some time, so that you're no longer a complete beginner. But it still seems like an impossible mountain to completely climb -- scales in 'formula patterns,' chromatic scales, 3 and 4 note chords in solid and broken forms, 4-octave arpeggios, etc. etc. What an impenetrable jungle!
Of course you cannot learn it all at once; you do it step by step. This is one of the many reasons teachers are so useful: They know what your next steps should be, and when you are ready to take them.
Have you heard of those famous music-teaching institutions, ABRSM and The Royal Conservatory (RCM)? If not, do a quick read about them on Wikipedia. Did you know you can freely download the complete piano-learning program, grade by grade, of each institution?
What's more, you can find Youtube videos of qualified people explaining and playing this material for you.
Example: Suppose you've learned all your scales, and you can plunk your way slowly through most of the 3-note arpeggios, and you think you're becoming pretty slick. So you skim through the RCM piano syllabus and find the Technical Tests for each level. On page 48 it says at Grade 5 you should be able to do the scale of A Major, two octaves, hands together, metronome speed 104, eighth notes (two notes per metronome click).
You find that you are able to do that easily! But as a careful student, you next fire up Youtube and find a matching video which allows you to compare your performance of this scale to that of an expert. You sound and look just like the expert! You must be the new Horowitz!
Next you find on p. 48 (and further along in the video) that Grade 5 also requires you to play some solid and broken Dominant 7th chords, which at this stage, you can barely find on the keyboard. Perhaps you are not the new Horowitz.
But you now have a simple and obvious indication of how to proceed: Go back down the grade levels, test yourself against the requirements, find the right videos, and start filling in the gaps.
Links:
RCM Piano Syllabus 2015 (this is the most recent version, they update every few years) -
https://files.rcmusic.com//sites/default/files/files/RCM-Piano-Syllabus-2015.pdfABRSM Piano Syllabus 2019 & 2020 -
https://us.abrsm.org/fileadmin/user_upload/PDFs/Piano_Syllabus_2019___2020_complete.pdfYoutube videos -- there are many useful ones, so just enter different keywords and you will find them. But here are two high-quality examples to give you the general idea:
"Grade 4 RCM Technique Requirements" -
www.youtube.com/watch?v=fh3DzDHwNE0"ABRSM: Grade 4 Piano Technique Requirements" -
www.youtube.com/watch?v=gA-hJhq-SvA = )