To cut a record at half speed, the engineer slows the lathe and the tape to half their normal rate. The cutting head has twice as long to follow every curve of the sound. Then the record plays at full speed, and the detail is still there.
It takes twice as long. Nobody who buys the record knows how it was made. They just notice it sounds right.
That is the trade we make with themes. We build one at a time. We test every section in the real editor, on a real phone, with a real catalog of a few thousand products. We leave out features that mostly exist to be listed. The result is a theme that your customers never think about, which is the point.