I actually recently went through a whole thought process about what I wear and how I could build my perfect wardrobe with 95% hand-made clothes. I kind of decided on an 80-20 rule overall for TNTs vs. one-off items.
I can't imagine ever owning a wardrobe that was 100% based on 10 patterns, but I could imagine one where AT LEAST 80% of it was, with novelty coming only from use of colour, prints, texture/fabric and minor decorative details rather than fundamental pattern differences.
The other 20% of my clothes I would expect to either buy because making them is expensive/complicated/annoying (e.g. swimwear, etc), or where I would want to have the option to play with lots of different patterns (e.g. evening wear or very trendy items that I fall in love with but will only want one of).
So then I decided to work out what my 10 base patterns would be, and of course ended up with 11 sewing patterns and 4 knitwear patterns.
1. Semi-fitted woven blouse
2. Relaxed fit woven shirt
3. Basic jersey top
4. Bootcut tailored trousers
5. Bootcut jeans
6. Wide-legged trousers (that can also be cut as shorts)
7. A-line skirt
8. Straight skirt
9. Armhole princess single-breasted jacket (can be lengthened to coat)
10. Woven dress that can be worn as smart-casual to formal.
11. Jersey dress that can be worn as casual to smart-casual.
And my TNT knitwear patterns would be:
1. Relaxed fit pullover
2. Form-fitting pullover
Then I produced a massive spreadsheet and sorted my whole existing wardrobe into two seasons (spring/summer, autumn/winter) and three colour co-ordinated collections, and then I made myself a plan for where my gaps are and what TNTs I most urgently need and what skills I need to learn to make my imaginary perfect 80:20 TNT:Novelty, 95%+ handmade wardrobe a reality. This year I really want to focus on tops because I get the WORST fit from RTW in tops due to my Boobs Of Immensitude.
... and that is more information than anyone ever needed about my clothes