This week I created the first prototype for a project I've been working on for two and a half years. I was given this task on literally my first day of work in late 2006. I had just changed professional fields. It took me that long to get the tools I needed to solve this problem.
Changing fields is normal, if not inevitable. Long ago a person entering a new line of work may have been looked upon with suspicion, as if they had failed, but now it's seen as a sign of growth and ambition. As a materials scientist, I've worked in three fields and I'm not yet 40 years old. In grad school I worked on thin film surface coatings. My first job was in friction and wear, which involved some wear-resistant coatings, but mostly not. In late 2006 I began working on semiconductor materials, which is about as far from lubrication as you can get while still being materials-related. My education provided the background for it all, but every new set of problems had to be approached with its own set of tools.
How long does it take to reach peak productivity in a new field? The hardest problems involve multiple interdependent challenges, and these are the problems people get hired to solve. You need to be at your peak productivity to solve them. If you've just changed fields, at first you won't even know what tools you'll need, but if you keep learning and stay open to possibilities you'll find a way. In my case, it meant learning about all the surrounding parts and assembly techniques that go into my company's products, and admitting that tweaking the semiconductors alone couldn't solve the problem.
Think back to the jobs you've taken, and the problems you were hired to solve there. Whether it was designing a next-generation product or getting two teams to cooperate or selling into a new market, they probably hired you to do something they couldn't figure out how to do. You probably weren't expected to show up and tick off checkboxes all day. If so, you probably got replaced by a machine before too long.
It takes time to fill your toolbox. Approaching problems as a stranger, though, can often give you novel ideas - and novel ideas are the kind that are needed when your employer's conventional wisdom didn't work. Best of all, as your career goes on, you build two advantages: first, broad practical experience; and second, mental flexibility.