This is a debate among many online instructors. Some say time tracking is a vital feature in an LMS, others say it is useless information and cannot be the basis of a grade. However, some educational mandates require some sort of time tracking.
The problem lies in what can be tracked in the NROC system: time spent in the course. This time log may not be in line with the reality of the student's behavior. The students might be logging "time" but not interacting with the material. They could be playing video games while the course is open in another window. We have taken steps to stop time from being logged when the student leaves the window, but this is still an imperfect situation. Conversely, a student could be interacting with the course, but not the material. They might open a reading assignment in a different tab, or open a different set of material. Both of these actions can stop the clock in the course. Some students just click around to keep the window from timing out, or they might have trouble getting something to load and keep trying over and over, but not actually working.
There is usually a way to get an idea of your students' activity level in the course by using LMS logs.
This will vary by LMS, but using Moodle as an example, you can get a general idea by viewing the Activity Logs. You can see where they went, and how long they stayed in any given place. For example, if the student spent one minute in Topic 2, this could indicate that they did not do the work -- or that they had trouble getting it to load. If a student spent 50 minutes in Topic 1, we do not know if they were struggling with it, watching it multiple times to "get it", or completely distracted and not interacting with it at all.
Because of these limitations, many teachers decide to grade based on learning, proven by scores on quizzes and homework assignments, rather than by time spent.