It's probably worth pointing out that W & N Series 7 red sable brushes are "top of the line" and are priced accordingly. Here in Australia you can pay up to $25 for a Series 7 000 brush, which seems ridiculously expensive to me.
I buy synthetic (taklon) round brushes in a variety of sizes (000 to 0) because they are cheap and easy to replace when they lose their point. I'm rather tough on my brushes, and I tend to paint in acrylics, so it makes sense for me to buy cheap ones and replace them regularly.
I do most of my acrylic painting with brushes sized between 000 and 2, so I tend to buy cheap ones and replace them often. I do have some better quality flat sable brushes which I use for painting with oils and some long round sable brushes for applying washes.
I bought three new taklon brushes today for less than $7. They will probably be thrown out after I finish my next project and then I'll buy new ones.
For beginner painters, I'd suggest you decide for yourself whether investing in W & N Series 7 brushes suits your style of painting and your budget
You may find you spend almost as much money on brushes as you do on figures. If that happens, I suggest you switch to taklon brushes and buy them in bulk.