Were I writing comedy of manners, or like Jane Austen, I could safely assume they were off-stage, and everything waits for the characters to attire themselves properly. (For one thing, they're changing themselves.) And once the Action and Adventure start, the heroine gets to wear what she had on for however long it takes. The heroine who favors artistic dress for contributing to her eccentric reputation also finds it handy in that respect.
It's the in-between stuff, where she is still feeling out the lay of the land and fathoming where to trigger the action and adventure that makes it questionable. To be sure, it gives her an iron-clad excuse to be off by herself, but still it can be awkward trying to slithering in spying and discoveries when you need four changes of clothing a day.