I'm now of the opposite view. You can take all this with a grain of salt, but I found this explanation convincing -
My own story is that I when I was diagnosed with Retinitis pigmentosa (1988), I was put on a bunch of antioxidants, and also bought, over the years, some others on my own. All of my ophthalmologists have told me it is better to get them from food and said to stop the pills. That happened in the nineties, early 2000'a, and I listened. My retinitis remains static, no negative changes since 1988. My "bad" eye is bad for other reasons (5 surgeries) but is also stable.
All time spent by an employee performing activities which are job-related is potentially "work time." This includes the employee's regular "on the clock" work time, plus "off the clock" time spent performing job-related activities (which benefit the employer). Potential work is actual work if the employer "suffered or permitted" the employee to do it. An employer suffers or permits work if it knows the employee is doing the work (or could have found out by looking), and lets the employee do it.