I've done it myself. I was with a small company for about six years. Over time, the focus of the company shifted away from what I was originally hired for, and

I've done it myself. I was with a small company for about six years. Over time, the focus of the company shifted away from what I was originally hired for, and it took me over a year to realise I was bored out of my brain. Resigned and went freelancing. Remained on good terms and did the occasional small bit of work for them. About six years later the company focus swung back and they approached me with a, "We need to redesign our entire tool-chain and reckon it will take about two years, are you interested?" I was, so said, "I might as well come back full time for that," and that was over six years ago now. They keep finding more stuff for me to do as technology bases are an ever moving target.