You should know where you stand from day one in a class. Just make sure you're never in a position to have to drop a class
That is more accurate advice. I always tell my kids the same thing - don't bite off more than you can chew and make sure you do your best in each class.
Unlike my stepdaughter, who parties more than half of the nights every week in college, back in the 70s I studied all day long, all evening long, 24/7, except possible one night a week on the weekend, unlike most college students. I took as many tough classes as I could swallow, NONE of them being anything less than the most challenging and relevant to my majors that I could find.
You seem to think that there is always more time available. At the time I dropped the one class I ever dropped, I was taking physics, honors calc. III, honors organic chem. plus the lab, and scientific german I. Around Thanksgiving I realized that I had gotten a "D" on the organic midterm since I had gotten behind and not studied 2 chapters very well, and there was another hourly exam the very next week covering 5 new chapters which I hadn't even read, and about 12 more chapters to go in the 4 weeks before the end of term. It just wasn't feasible with the amount of memorizing required.
When I first signed up, yes, theoretically I could handle it, but practically, every waking hour was not enough to ace all of these classes. After dropping organic I got A's in the other 3 classes, and kept a very strong A- average well into my junior year.
One other thing I always tell my kids about college, all professors are procrastinators when it comes to pacing the class progress through the syllabus. There might be one chapter covered in the first week (which is usually BS anyway), 2 in the second week, but by the end they are throwing 5 chapters a week at you.