Responding to a PM on the note of pacing!
Given the computer adaptive nature of the test, pacing is an essential element of overall success on the GMAT. It's also important to note that not every question is designed to take precisely the same amount of time to solve, so pacing should be developed with the objective of maximizing the impact of your time as a whole in the section. Remember, you can afford to miss questions and still be extremely successful on the test... you can't afford to be stubborn and maximize your success!
So, for proper pacing on the GMAT, I suggest applying the following benchmarks (question numbers at which you check in on your time position):
Quant
(since we'll want to spend about 2 minutes per question on average, check in every 5 questions at 10-minute intervals)
Question - Time Remaining
5 - 52
10 - 42
15 - 32
20 - 22
25 - 12
Verbal
(Here, we have closer to 1.8 minutes per question on average - so the numbers don't work out quite as nicely, but you can always note down the benchmarks on your scratch pad at the start of the section and refer back to it)
Question - Time Remaining
10 - 47
20 - 29
30 - 11
Keep in mind, these are the times you should be looking for after completing the noted question. These are also general benchmarks - if you're within a few minutes of the benchmark, you should be in fine shape. You'll notice that I've suggested less frequent benchmarks in verbal. This is by design, as benchmarking too frequently for verbal can often cause undue stress if, for instance, you check your pacing after the first question of a reading comprehension passage. In that case, you'll likely reflect as a bit behind on pacing, even if you're realistically in perfectly fine shape. That said, if you notice you're falling substantially behind in pacing with the 10 question benchmarks in verbal, feel free to adjust to every 5 questions with 9 minutes subtracted at each 5 question interval.
You'll also want to keep in mind that the benchmarks are designed to guide your question-to-question approach, and specifically, how you make the distinction on how to proceed through the question after about 20 seconds or so of analysis. So, if you're falling behind - don't guess at random to catch up. Instead, try to identify an opportunity or two on a question that appears prohibitively time-consuming, or to which you don't see the approach after analysis. From there, you'll want to make a quick, educated guess based on any secondary strategies you might be able to apply (backsolving, number picking, etc.) and move on to apply the remaining time on questions you'll have a higher potential to be successful on!
Remember, the key to pacing is investing as much time as possible on questions that have the opportunity to add value to your overall score!