it's hard for me to get past the sleep advice, it sounds misguided at best. Sure there are studies if you google oversleeping, they define it as sleeping over 9 hours a night and it sounds it usually is associated with low quality sleep. The core issue is what is causing low quality sleep, oversleeping is a symptom to compensate, and it doesn't sound like 7 to 7 and a half hours is the sweet spot, it's 7 to 9 according to the National Sleep Foundation Guidelines[1].
I concur. The vast majority of people have the exact opposite problem and sleep too little, therefore the general advice would be to get at least 8h of quality sleep per night.
It threw me off the whole article as well, it's hard to take it seriously when it hits me with "don't sleep too much" in the beginning, especially since I've always been somewhat of an insomniac and I'm intimately familiar with the impact of sleep deprivation across all aspects of one's life.
They do mention that sleeping too little is also a problem. Sleep varies so much from person to person that it is often controversial. It might be better to think of that point as advising you to try to optimize the amount of sleep you get. That's more of an experimental process where you find out how much sleep you need and how to get it i.e. what do you need to change in your life in order to sleep better.
“Worked for me” in the title is important here. For me this is great advice. I have exceptionally low cortisol levels and have accidentally slept for over 24 hours many times in my life. Without an alarm I generally sleep for 16-18 hours, those days suck because they’re too short to get much done.
Sleep is like diet, it’s different for everyone. I’ve trained myself to lucid dream to try to make the most of the days when I oversleep but it still sucks. The point seems more like maximise for time when you’re actually accomplishing things. What’s healthy for each person is different.
[1] https://pubmed.ncbi.nlm.nih.gov/29073412/