Interesting thread and enjoyed reading people's processes. A few questions...

Working on my first 'serious' project, I find that I'm commited but hasty about 'getting it done'. I seem to have a lot of ideas, which can change at a whim and perhaps I'm conscious of this when starting a project - hence blazing through before another idea gets in the way. I'm always surprised to read about photographers working on multi-year projects, but I suppose this length of time is determined by other responsibilities more than anything? Ideally, would you get it done in a few months without the other 'distractions'?

Someone else mentioned going back to books and other photographers when ideas are running dry on a particular project, but isn't there a risk of this completely changing the trajectory of your work? With my current project I'd spent a few weeks making notes and poring over books. Loaded with inspiration I then started shooting. If however I was to discover the work of somebody else doing something similar, rather than take from it and re-develop my own work, my tendency would be to think "it's already been done" and move on to something else. Is this creative ADHD or do other photographers constantly experience this uncertainty?

How do you really know when your project is worth the time and commitment when, potentially, you could have spent that time doing something else much better and more original?
It makes me wonder if those notable photographers really are blessed or perhaps just lucky in stumbling on an original idea.