Welcome to the forum! You ask some very good questions, and it seems that you are getting great advice, I am following this thread with interest.
Unfortunately, I don't think I can offer you very specific advice myself, as I don't think much in "capsules"--in fact, like some others here, I often find this term (or the ways it is used) somewhat confusing. However, I am willing to share some of my own dressing concepts with you:
I prefer to dress in a mix of neutral and non-neutral colours. (My neutrals are cool brown, white, grey --light, medium, dark and silver--and black. And my non-neutrals are cool and clear, ranging from lemon, via pink, blue-reds and violet to blue, turquoise, teal and forest green.) I make sure that I have at least one, preferably two or more, neutral items in each category (pants, skirts, pullovers, blouses, jackets, shoes, boots, etc.) Then I'll add non-neutral accessories and/or a top. Or I might start with a non-neutral dress, skirt or pants and then "calm it down" by adding non-neutral accessories. There are lots of possibilities. I will happily wear more than one neutral and one non-neutral in an outfit. If wearing a printed scarf, for example, I may choose to wear clothing items and accessories in various colours found in that scarf.
Apart from neutral basics, I don't think I need to wear several items in the same colour. For instance, wearing a hot pink pullover with an otherwise neutral outfit may be enough. On the other hand, there's nothing wrong with pairing that pullover with a colourful scarf and/or shoes.
I feel OK wearing any of "my" colours on the upper part of my body. However, when I wear a bold colour on the lower part of my body (pants, skirt, shoes, hosiery), I find that repeating that colour somewhere near my face helps creating balance in the outfit and directing the attention to ME (my face, my eyes), not just to the ensemble. Tip: This is extra important in situations where you want people to pay attention to what you are saying.
For example, cobalt blue shoes could be balanced by cobalt blue earrings or a cobalt blue blouse or jacket, or simply by a patterned scarf where cobalt blue is one of the colours.
I don't feel it necessary to buy a lot of things in the same colour. But if I buy for example a pair of cobalt blue shoes, I will make sure that I have at least 2 things for my upper body (a top, some jewellery, or a scarf) in the same colour or with the same colour represented in a print/pattern.
And I do the same when packing: If I want to bring for instance my red pants, then I'll make sure to also pack my red necklace, a printed red scarf and perhaps a red top and/or cardigan. Then I know I will be able to combine these items with items in several other colours (neutrals as well as non-neutrals) while still having cohesiveness and balance in my outfit.
Maybe you can use some of these ideas.