Echoing what no doubt many others have said,
1. Belief
How deeply your subconscious can be impressed with the inevitability of the outcome / how much blind “faith” you have that the outcome will manifest, no questions asked, no “how” or “why”, just knowing that it is done.
Refusing to act as a “hostile observer” to your own outcome by obsessing over it in thought or in deed.
Coming to peace with the idea that even if [outcome] doesn’t happen, I will be OK no matter what.
2. Mindset
How well you can sustain the belief that your outcome is inevitable, even in the face of evidence to the contrary, even when results don’t appear as quickly as you’d like or nothing seems to be happening.
Your ability to persist in practicing magick despite failure.
Your definitions of “failure” and “success”.
Your expectations of magick. Magickal outcomes are likely to happen in ways that seem natural and coincidental, to the point where you may doubt you had anything to do with it at all. Magick follows the path of least resistance. If you cast a death curse on someone who loves to go skiing, and three months later they die after skiing off a tall cliff, you’re probably gonna think “ah, who knows if that was my death curse working, that could have happened anyway.”
The only workings I’ve done which I consider to be 100% failures, are the ones I’ve specifically attached a time frame to (e.g. “X will happen within 3 days”).
See the below, as well:
4. Probability
The likelihood of your outcome occurring without any outside interference.
This is why it is encouraged to break a large goal down into smaller occurrences and cast a ritual for each one of them.
It is also why you are encouraged not to put too many restrictions on your outcome.
Say you want money and you perform a ritual for “I win the million dollar lottery”. This means you are placing a specific restriction on how you acquire a million dollars (it must be from winning the lottery). “I am a multi-millionaire” is better, but still quite a large goal which should be broken down and worked on long-term (see above).
Again, like I said above, the only workings I count as 100% failures are the ones which I attached a time frame to. Funny thing is, I did perform some rituals which I’d asked for in a time-frame of sorts, but I had a specific target in mind (e.g. “X took me on a date to Z event”. Those ones came to fruition exactly as I asked, but not with the intended target. 
Why? Probability, path of least resistance.
Refer back to my “death by skiing accident” above. If you cast a death curse on an introverted agoraphobic who hates exercise/sports and is currently in lockdown, the probability of them dying in a skiing accident is very low. And if you do cast a ritual for this person to die specifically in a skiing accident, you’re probably going to be waiting a while for events to line up to make that happen.
5. Practice
How long you’ve been practicing magick.
The development of your own paradigm/worldview.
Commitment to being open to the current of magick.
Ties into Belief.
6. Technique
How much effort you pour into a ritual. The difference between putting all your focus into performing a ritual vs. just glancing at a sigil and reading a few names off a page while you’re also idly thinking about what to have for dinner later.
Ties into Persisting.