Generation takes seconds. You upload, choose what you want, and the result comes back quickly enough that comparing several options is practical rather than tedious.
That speed is the real advantage over both a physical fitting room and a traditional photoshoot, and it changes how you use the tool. Trying the same garment in three colours, or comparing a regular and an oversized cut side by side, costs almost nothing. In a fitting room that is a queue and ten minutes; here it is a few seconds and a second tab.
Everything runs in the browser. There is no app to install and no desktop software to configure, which also means it works the same on a phone as on a laptop.
If a generation is taking unusually long or returns something obviously wrong, the input photo is the usual cause. Very large files, extremely low-resolution images, and photos where the subject is hard to identify all add work. Re-shooting a clean reference photo fixes it more reliably than retrying the same input.