In watercolour veil-painting therapy (Liane Collot d'Herbois) it is critical to get the right colour since blue is not just blue, but either turquoise, cerulean, cobalt, ultramarine indigo(and a prussian you want to avoid). I use a lot of WN too, it is a very reliable quality, but for some colours I had to go to other brands (Schminke for scarlet and vermillion). Another thing to be mindful is that the names don't always give you the true colours. It's a matter of trial and error. Cobalt Violet is incredibly difficult to get right for the purpose of veil painting (not too pale but still heavily diluted, since therapeutically it's about the - etheric - water-sensation too).
Thank you for making a useful start on making people aware of all the tricky aspects to painting in water colour. It is often considered an inferior way of painting, but so much can be done with this medium.