1. Answer all questions that I know the answer instantly or (for math type tests) can solve within a few seconds. Skip anything not quick. 2. Go back and answer questions that I know I can solve. These usually take a minute or two (since the easy ones should already be done). If there happens to be a question I know I can solve but also know will take "too much time," skip it. 3. If there's time left, work through any remaining questions (hopefully there aren't that many), making a best effort to prioritize the ones I'm more confident that I can solve in the time remaining.
It's a good lesson, but it's a lesson about taking tests not about the material. I can see arguments for and against including that in any given class.
In some tests I have seen future questions answer previous ones. For a contrived example:
"Q1: What color was the bookshelf? A. Red B. Green C. Blue"
"Q2: What sentimental item did John take from the red bookshelf?"
I was never sure if it was on purpose to reinforce reading all questions before answering or if it was merely poor test design. Usually it was more subtle than my contrived example but it did bump my scores on some tests up a bit.