I learned the value of patience and moving slowly through many mistakes where I moved too quickly.
In the startup world, the default is to move as fast as you can, and it's often easy to mistake a maxim for product development as a maxim for life. The problem is that it's not good advice for many things in life. Examples:
1. Shopping. Especially big ticket items like cars and places to live. Urgency favors the seller because you don't do diligence well and you don't shop around for better deals when you're in a rush.
2. In a similar vein, negotiating. I got screwed on deals because I felt too much in a hurry to bring up issues I had. The important point here is that I could afford to wait, but I didn't want to, and that worked against me.
3. Job searching. Taking the time to line up offers will pay returns on your salary and happiness, even if in the moment you really just want the job search over with.
4. Managing people. I've had people who work for me ask "how am I doing", and in my urge to avoid the awkwardness of the conversation, I would answer some variation of "fine" even if in my mind I knew there were problems. The problem is that answers like those are very hard to take back once you give them (and especially hard to take back during performance reviews). So instead of trying to get rid of the problem fast, I eventually learned to step back and say "let me think about this, and let's talk about it tomorrow."
5. Relationships. If your goal is to find a life partner, you have a lot of diligence to do. Enjoy the honeymoon period, but don't mistake that for deeper compatibility. That comes from spending time together and requires getting through rough patches together as well.
6. Professional relationships too: on the one hand, you can't be passive in developing your professional relationships, but you can't rush them either. Respect is earned over time, so you have to play the long game.
When it comes to building products, then yeah, moving fast is an asset, but many things in life and career are marathons, not sprints, and you're just hurting your future self if you outrun your own pace.