Why do they have skill books for only some types of skills in the Sims? I have a Sim who's an Angler and I'd really like her to be able to improve her fishing skill, but she's a single mother with a Teen and a Toddler, so she can't leave her kids alone. After all, babysitters don't help with anything. It would really help if there was a skill book for Fishing, so that she didn't have to drag her kids to a fishing spot and ignore them for a couple Sim hours while she fishes.
But skill books are also really helpful. If your Sim is really busy, or, like I said before, can't really leave because of young Sims, they can just read a handy skill book. Or if you're just really, really lazy and you don't actually want to make your Sims do any skill work because it takes a long time, just have them read one and set the time settings to fast forward.
You can get a Sim up to Level 9 in any skill that has a skill book in 2 or 3 days, depending on what level they already have, really easily!