Philip Larkin says

I don’t think you can write a poem for more than two hours. After that you’re going round in circles, and it’s much better to leave it for twenty-four hours, by which time your subconscious or whatever has solved the block and you’re ready to go on. The best writing conditions I ever had were in Belfast, when I was working at the University there…. I wrote between eight and ten in the evenings, then went to the University bar till eleven, then played cards or talked with friends till one or two. The first part of the evening had the second part to look forward to, and I could enjoy the second part with a clear conscience because I’d done my two hours…. I wrote short poems quite quickly. Longer ones would take weeks or even months. I used to find that I was never sure I was going to finish a poem until I had thought of the last line. Of course, the last line was sometimes the first one you thought of! But usually the last line would come when I’d done about two-thirds of the poem, and then it was just a matter of closing the gap….

You write because you have to. If you rationalize it, it seems as if you’ve seen this sight, felt this feeling, had this vision, and have got to find a combination of words that will preserve it by setting it off in other people. The duty is to the original experience. It doesn’t feel like self-expression, though it may look like it. As for whom you write for, well, you write for everybody. Or anybody who will listen.

I shouldn’t normally show what I’d written to anyone: what would be the point? You remember Tennyson reading an unpublished poem to [his friend of 40 years, Benjamin] Jowett [,Master of Balliol College, Oxford]; when he had finished, Jowett said, “I shouldn’t publish that if I were you, Tennyson.” Tennyson replied, “If it comes to that, Master, the sherry you gave us at lunch was downright filthy.” That’s about all that can happen.