Just because you've learned how to draw or sing or code and made beautiful things previously, that doesn't mean you're going to be able to summon your max skills every time you sit down to do so. Even the most advanced artists can find themselves stuck performing like untrained children at the start of a session. It's by warming up that we gradually summon the relevant knowledge to the top of our minds and prepare our bodies to make the necessary motions from our muscle memory.
Many budding artists think they're not improving because their outputs always seem the same, but they're judging their progress on what comes out in the first five minutes of a brief session, only to end up quitting without ever seeing what their actual skill level is.
How long it takes to warm up will vary from artist to artist. It depends on a variety of factors, from their personal health and temperament, to the frequency with which they perform, to the complexty or oddness of the project they need to work on that day. Someone who performs similar assignments daily may only need a few minutes to warmup, whereas someone who only engages occassionally in passing may need hours to reach their actual skill level in their output. The primary benefit of daily practice is to reduce warmup time, not to speed up learning.
We can also have days where no amount of warming up is enough. Maybe we just don't have time due to deadlines, or maybe it's a bad art day. In these situations, you may have the option to put off the project to a day where your work is coming out better, but you will otherwise need to push through and deliver something below your standards. By delivering something, you have a draft that you can get feedback (https://lib.hol.ink/index.php?topic=43.0) on and iterate if needed, and the client has the chance to move on to the next step of their project if it's good enough for them.
The use of the warmup concept in art comes from multiple different origins. There is the physical act of warming the body up before exercising with light cardio, which increases bloodflow to the muscles, promoting healing and flexibility. And there is the psychological act of warming up to becoming increasingly alert, eager, and interested in an activity. It is not one distinct practice, and each person's methodology for getting warmed up to perform their art will vary depending on their needs.
For visual art, I would usually recommend drawing for a short period without judging the outcome. You want to exit the mind and be more of an external observer to what is happening. This can present as full-blow automatism (https://lib.hol.ink/index.php?topic=41.0), but it can also just be an intentional choice to hold back judgement as you practice. It's perfectyl normal for your warmups to look bad, and you shouldn't tie your value as an artist to your output quality or beat yourself up over it anyway.
You usually want the method you're using to warmup to mirror tasks you'll need to be performing in your art later. For example, if you mostly draw with straight lines, warming up with swirls will probably not be enough. On the other hand, if you're about to do a bunch of swirling calligraphy, warming up with only straight lines will probably not get you very far. If you're about to do character designs, warming up with landscapes is bringing the wrong information to the front of your brain.
These unrelated activites may still help with your warmup process, however, and you should do them if it's all you can bring yourself to do in that moment, or if they're providing satisfaction (https://lib.hol.ink/index.php?topic=40.0) that helps you continue drawing. Anthing that keeps you going will be more efficient in the end than the theoretcial "ideal" solution.