Clear coat is finite. A factory finish is roughly 40 to 60 microns of clear, and every correction stage removes a measured amount of it. Spend too much and there is not enough left to protect the color underneath, which is a problem no product fixes.
So the real question is not 'how perfect can this get' but 'how much clear coat is this result worth'. On a car you are keeping for a decade, leaving room for a future correction is worth more than the last two percent of gloss today.
This is also why we measure and look rather than quote from a photo alone. A car that has already been corrected twice by a previous owner may not have the clear coat to support a two-step, whatever its swirls look like.
The related point: correction is far more valuable when it is protected afterwards. Corrected paint left bare re-swirls quickly, which means paying for correction again sooner, which means spending clear coat again. That is the practical reason our correction always comes with at least a 12-month sealant.
The pattern we recommend most often is one step plus a good sealant or coating. It is the combination that produces the biggest visible change per dollar and per micron.