Is this something only I understand after growing up?

I wonder if anyone else feels the same way I do. When I first started my job, as soon as quitting time arrived, if my boss hadn't left and my colleagues hadn't left, even if I had finished my work, I wouldn't dare be the first to pack my bag. I always felt like the person who left first was 'not trying hard enough' or 'trying to slack off'. After changing jobs a few times and seeing different bosses' reactions, I finally saw a harsh truth about the workplace: 'Those who leave quickly at the end of the day are often the truly capable ones.' Half of the people who habitually stay late are slacking off, and the other half have poor work efficiency. Conversely, those who can disappear on time demonstrate clear goals for the day, sufficient stress tolerance, and the ability to get things done within the allotted time. Your boss might not say it, but they actually respect these individuals more. If you're still 'acting' busy in front of your boss at quitting time, you can stop now. It's a complete waste of your life. Now, as soon as quitting time hits, I'm always the first one to grab my bag and leave. I want to ask, are you brave enough to leave right on time now? Or does your company have even worse 'unspoken overtime rules'?