Yoyo string is kinda like toilet paper. Eventually you are going to use it.
I buy Kitty string 100 packs; 4 packs at a time. I use regular, slim, fat and 1.5; depending on the yoyo set up.
My primary string is the Kitty 1.5
…If you change strings often(like I do); 100 strings isn’t really that many. I prefer strings with a little ‘life’ to them. So as soon as a string feels kinda dead; I change it out. I don’t care if it looks brand new. That dead thunk feeling is especially noticeable in looping yoyos. When the yoyo hits the end of the string with a flat feel; it is done for me. I prefer Kitty fat or regular for looping. And Slim or 1.5 for 1A and 5A.
Some people keep using the same string until you can almost see through it! Or you can’t really tell what color it was. Or it gets so slimy or slippery; they change it out even if they don’t want to.
Pretty much All yoyos actually feel ‘more alive’ with a new string. As the string is used; the performance decreases slowly. With experience; you will be able to recognize when the yoyo starts acting sluggish or feeling klunky. < Then you change the string.
I do not hesitate to buy a 10 pack; if I really just want to try out a new string.
But if it something I already know that I really like; 100 packs are automatic.
…Also; there are a few strings I buy in 10’s just because they are excellent for certain yoyos. One is YYSL Venom. The other is the YoYoExpert Core string.
I should note that presently it is very difficult to buy a Bad string. Most Makers have to make pretty decent string just to stay competitive.
But strings ‘do’ have various performance strongpoints. You may have a certain style that just comes out better when you use a certain string.
Finding the right string for you is kinda like trying on shoes until you feel like the shoe is part of your foot.
If you have an idea of what may work for you; then a 100 pack is the most economical way to go.