On the other hand, I like that I can go from one project to another when I get bored or frustrated with one. I can also go back and forth between knitting and crochet, again for the same reason. Even within items that are all crochet or all knit they are very different projects, again giving me a lot of variety.
For instance, the house slippers are made using an J sized crochet hook, the teal colored one.
As you can see it is larger than the hook next to it. In comparison the shoulder shrug uses an H hook, considerably smaller (the smaller pictured hook in gold). That means that even though I am making similar movements they are different because the size of the hook dictates the size of the loops and how much movement I have to do to make it all work. These patterns also use different stitches. The slippers are using almost exclusively a half double crochet (hdc) whereas the shoulder shrug uses a double crochet (dc).
The different sized hooks make different sized stitches. The larger, naturally, make larger stitches which can be beneficial for a large item or one where you want larger holes for whatever reason. Crochet hooks range massively in size. The finest (which I didn't take a picture of) are used for lace and other very small scale items. The larger ones are used for clothing items and larger items.
Here you can see the difference in sizes. These are kind of the "normal" or most commonly used sizes for most people. The gold one, the "H" hook is probably the most used hook just because it makes stitches that are a nice size for a lot of different projects. However, they go well beyond this size.
It is hard to see just how much bigger the bottom hook is, but it is significantly larger. That is an "S" sized hook - I have used it to crochet a border with 4 strands of yarn on a throw blanket. The other two between the full metal hooks and the S hook are "L" and "M" hooks. I have used each a few times, sometimes for a starting chain because I tend to chain too tightly (which often is what starts a piece of crochet work)!
Patterns will almost always indicate which size hook that you should use to achieve the same look as the item in the pattern. However, depending on each person some people crochet tighter/smaller stitches with the same sized hook than others. So you have to check your "gauge" which is how many stitches you have per inch. I tend to have rather tight/small stitches so I often have to use a hook of a slightly larger size to achieve the same desired look.
When I first started all I purchased was a size "H" hook. Once I realized that I really liked crocheting I went ahead and bought a basic set which included all of the hooks from sizes "D" to "J". I got most of the others from thrift stores as single items because it is, naturally significantly cheaper. I will show off my knitting needles some other time, almost all of which I purchased exclusively at thrift stores.
In the meantime, hopefully that helps some (like my brother) who doesn't understand it when I say that I used an "S" hook to make big stitches so it went quickly.