A capsule wardrobe built around too many brands ends up as a pile of pieces that don't quite match each other - the real value of the concept comes from choosing a small number of brands whose fit, fabric, and style genuinely work together.
A brand whose sizing and cut consistently works for your body removes the guesswork every time you shop, which matters more long-term than any single item's design.
Building the capsule around whichever category gets worn most often - basics, outerwear, workwear - produces a more useful wardrobe than starting with statement pieces that get worn rarely.
A capsule that's too rigid stops feeling like your own style. Reserving one category - accessories, a single standout piece per season - for genuine personal preference outside the core brand set keeps the wardrobe from feeling like a uniform.