Colour is a bit of a trickster. It changes with light – morning sun, harsh afternoon light, soft evening lamps, cloudy days, all shift how a shade looks. A colour that feels calm and neutral at noon might turn greenish, dull or surprisingly bright at night.
By painting test patches and checking them at different times of the day, you see the full personality of the colour in your actual space. You might realise one shade always looks slightly dirty in the evening, while another stays pleasant throughout.
This saves you from committing to a colour that only looks good for two hours a day. Since repainting a whole room is more work than testing properly beforehand, a few days of observation is a very smart investment.
