I agree with the points mentioned by fellow members. I just wanted to convey my thoughts on OOP/Software Structure Knowledge and how experience can or in some cases cannot bring that knowledge. If I am working on a product continuously, I am getting better at the same software I am working on, but not necessarily becoming better at OOP/Software Design because I would not know what's outside. You are lucky if you get to work on a variety of projects that have different development stages or framework etc on a daily basis then the experience working with diverse software will be invaluable to OOP/Software Design. But if you get to work on the same software (such as maintaining and minor enhancement), you could look at completely different language/framework and start making side projects. I find this approach very useful because when I start to learn new language/framework then I have to set my mind at '0' and then I get the way that I have not been working with. For example, working with Android Development in Java made me better at background tasks and multithreading which I rarely use in my regular .Net work and I started to use the techniques I learn in Android/Java in my .Net/C# development.