You can even take breaks due to the mental strain involved. It can be as challenging as explaining politics to a caveman or trying to gain acceptance as a leader in a rural area with a different culture and limited literacy. By offering your energy and soul power, you are essentially demonstrating your commitment to them. You might wonder why not choose a river or an ocean instead. The answer is simple: understanding your limits is Part of personal growth.
If a small lake represents a village of illiterates, a river could symbolize an entire country of such people, and an ocean would be akin to a continent or world populated by them. The overwhelming magnitude of such would simply melt your mind.
However, there are numerous benefits to this approach. Creating a domain requires less energy since you are utilizing the world's resources. Additionally, you gain unique advantages as the properties of the element you choose for your domain become yours. For instance, if you transform a poisonous lake into your domain, you now possess two types of water-based attacks in your arsenal.
The first approach is easier in the sense that you use your own energy to create your domain, allowing for a faster process and less mental strain. However, you may still encounter the challenge that your chosen element also very stupid, although it does respond better to your commands. The drawback here is the energy cost.
On the other hand, the latter approach involves refining your energy with the element already present. In this case, you use your energy to maintain, expand, and refine the existing element simultaneously. However, each domain must meet specific size requirements before your soul space can open, granting you the ability to carry it wherever you like. If your energy fails or your concentration wavers even for a second, you would have to start all over again.
In the first approach, your energy control and mental fortitude greatly increase, but you are likely to fail the initial trials. In the second approach, your mental strength increases greatly as you deal with a group of fools that you must recruit successfully, but you can take breaks from their stupidity. Therefore, it would most likely take a few years before your domain is successfully completed.
In reality, you gain just as much mental strength increase in the first option and even better control over your energy compared to the second option. However, most people still choose the second option more than half the time because waiting a few years to gain an extra property to your element is an incredibly cheap price for beings that would live hundreds of years.
And once you have completed the minimum mass for your domain, if not, the domain you have created is not fully developed, and therefore you waste energy maintaining it while searching for additional elements to incorporate into your domain. However, if that is not the case, you would seemingly carry your domain with you wherever you go within yourself. Despite meeting the minimum requirements, your domain is far from reaching its full potential within you, so you continuously add to it.
Your domain does all the work, but unlike if you had mastered poisonous water, you could continuously add all types of poisonous and normal liquids to your domain, giving you a larger arsenal or even combining them all to create a super poison. However, if you only master clean, natural water, you cannot add poisonous liquids to your domain, as your domain only knows how to refine natural, clean liquids.