We are never too old to learn. Learning is growth. And to grow is good. But that doesn't always happen. Often, and I know this is often true with me, we allow arrogance and insecurity to stifle our growth. We assume that, after many years of being a photographer, we know it all. We are experts, and experts need no help. Nothing could be further from the truth.
While not always successful, I do try to have an open mind with regards to my photography and my processing. If I see a photograph which speaks to me, I often try and decipher the technical process to see if there is anything I can apply to my work. Not that I copy somebody's work, but I might use it for inspiration. Usually it is not a new technique or gimmick I respond to, but an overall technical excellence.
See, as photographers we usually work alone. It's something we all love, but the risk is that we may, over extended time, develop bad habits without realizing it. Looking at the work of others, or reading their books, can often help us gain a useful perspective on our own work.
So we should not be afraid to open ourselves to input. Input is learning.