Well it depends.I was at a big company and it sucked. We had two hour meetings on folder structure of our repository. I was depressed, thought i couldn't possibly do anything worthwhile anyway.Finally I just quit my job and sat at home for 3 months. While I did consider starting my own thing, my confidence was so shot that I could hardly trust myself to do something. After some time, I joined a startup through a job posting on HN. Its been great so far. I have written more code in 2 months than i wrote in 3 years. Apart from that working with two of the most intelligent and well rounded people I know, I have learnt a lot technically , have had a lot of autonomy and have gained a lot of my shot confidence back. While I understand this is a personal experience and may not hold true for all, for someone wanting to start a startup, the second best place(best being of course your own startup) to learn is at a startup.