How long do you think it's appropriate to wait on a response to a requested full before withdrawing the manuscript and perhaps submitting to a small press? I've checked in every three months or so and received friendly "I'm getting to it" replies. In January it will be two years since the original request. I did send a revised manuscript (with the agent's permission; she hadn't started reading the original) but that was more than a year ago.
I understand that everything in publishing takes a long time, but while I've been waiting for an answer from this agent I've had time to write four novels (and revise and polish two of them). I'm wondering if I should close the book on the first manuscript (a travel memoir) and start over with an all-new agent search--or even release the novels on my own to avoid another two-year limbo. Basically, I'd like to hear your thoughts on finding the balance between being patient and continuing to wait on someone who has been stringing me along for years.
There's slow, and there's glacial and then there's stasis. Two years is stasis. Two years without any intervening communication (editing notes, suggested revisions) is a real brake on any momentum in your writing career.
Have I had fulls and partials for a year or more? Yes I have. Do I now? No, I do not. I have learned that if something hasn't caught and held my attention it's better to let it go. Not every good project is suitable for every good agent.
I think one year is long enough to wait for an answer on a full manuscript. Absent any kind of encouraging words, there's no reason for you to wait.
Of course, my advice is to start querying with your best new work rather than self-publish, but you should decide what your career goals are and what publishing strategy is most likely to accomplish those goals rather than just follow my advice blindly.