The essence of the operation

Hello, Honorable Rabbi, why is it that in some halakhahs it can be seen that the example is less important for the observance and only the essence of its action is addressed, and in some cases the example of the action is left even though it is irrelevant (and I am not talking about the reason for the halakhah, i.e. the answer to the question why). I will explain with a casual example, for example:
-Example of the action- You need to take a shower with sheep fat soap once a week.
-The essence of the operation- maintaining cleanliness.
-The purpose of the action- God commanded cleanliness.
 
And now an example from the halakha:
Three things a person says on Shabbat Eve…. Since these things are less relevant today, we return to the essence of the action, which is to make sure everything is ready for Shabbat.
Another example
For those who say that Ezra’s rule about washing on Thursday is because Friday should be left free for Shabbat needs, there are those who say that today it is possible to wash because washing takes a short time in an electric machine. Again, this refers to the essence of the action and not to the example of the action, and the essence can be observed even if one does laundry.
On the other hand
The prayer of Ma’in Sheva is still said even though the pattern of action is no longer relevant and the essence of the action is generally protection from danger according to the Babylonian at least (which is indeed relevant at all times but does not have to come in the pattern of the action of Ma’in Sheva)