In retrospect, I was at an agency for two years before moving to my most recent job at a product – I agree with you that being at a product gets you back to your core engineering skills, however, in the right environment, an agency can expose you to a lot of things you would not otherwise explore in a very short amount of time.
You're entirely right that you get used to delivering working solutions that are ultimately one-off fixes, but at the same time you also discover how to use technologies that speed up your production in a more pragmatic fashion. It's definitely not a product lifecycle, it's a project lifecycle – different but not any less valuable.
Although, it is unfortunate you have no coworkers. The thing I miss most about working at an agency is being able to poll my many developer colleagues to research and discover different approaches to problems. The fast pace of an agency often means that you aren't the first to discover a problem that occurs on a project, and your colleagues are a highly valuable commodity that you don't necessarily get at a product.
You're entirely right that you get used to delivering working solutions that are ultimately one-off fixes, but at the same time you also discover how to use technologies that speed up your production in a more pragmatic fashion. It's definitely not a product lifecycle, it's a project lifecycle – different but not any less valuable.
Although, it is unfortunate you have no coworkers. The thing I miss most about working at an agency is being able to poll my many developer colleagues to research and discover different approaches to problems. The fast pace of an agency often means that you aren't the first to discover a problem that occurs on a project, and your colleagues are a highly valuable commodity that you don't necessarily get at a product.