Erh... no. Of course I cannot talk about the teacher's view, but I sure can talk about the "other end". On both accounts.
First and foremosts, tests don't motivate students. They are, generally, a nuisance and something you want to get out of the way. Basically your goal is to get a passing grade with the least effort necessary. Unless of course the subject interests you in the first place but then you sure as hell don't need any encouragement, let alone in the form of a test. So what do you do? Well, you start learning for the test. To the test, more specifically. If you're in any way smart, you see through the formula these tests work at quite soon. For me that was more or less accomplished after elementary school, and you may guess that it was trivial to get passing grades with little to no effort for the rest of my school "career".
In short, tests don't show you whether the student understands the matter. It shows you whether the student understands the system and knows how to game it.
Second, and that's my far bigger beef with our school system, you talk about "practice their (children) weak areas". Why? Why the fuck is that even remotely sensible?
My weak area is languages. You might be able to tell, English is by far not my first language. I sure as hell loathed French and don't even make me start on Spanish. I hated every single second of it. Yet that is where I had to spend most of my study time. Because that's where my "weak" areas were. In math, physics, chemistry, history, I shouldn't be doing much. Those were the fields that were interesting to me, and hence my grades were pretty decent. But no, you should not concentrate on what you're good at. Concentrate on what you suck at.
Tell me: How the hell does this remotely connect with the real world outside of school? When was the last time your boss said "Oh gee, you're a great engineer, you can do the work of two mediocre engineers easily, but you really suck at marketing. So I'll put you into marketing for the time being 'til you improve at selling stuff."
Ever happened to you? No? Gee, why could that be? Could it be because your boss doesn't want you to be average in everything but rather an expert in the area you're working in? Because that's what EVERY business in the world would want from you? Being the best in your area, screw the rest?
But out school system is the exact OPPOSITE of what our economy demands and expects: It tries to make you average in everything. Instead of nurturing you in the fields you're good at and keep your focus on what you excel in, you're expected to let that slip and become mediocre in favor of the stuff you cannot do so well.
And as long as we keep this backwards system in place, don't expect the economy to improve any time soon!