I agree, writing and posting in chunks does cause issues with a strong, clear, fast-driving through line. I end up with zigzag stories and odd slants on t hings sometimes. Also, there can be a sort of weird out-of sight out-of-mind challenge there--if I posted it, it's done, right? I don't need to look at it again. Makes it too easy to forget bits and pieces I meant to deal with. I tend to obsessively go back and reread bits to get back in the groove, which helps a lot to solve that problem, but then committing to working on the next bit takes digging back into that older material and dealing with possible comments on it.
When I edit comments I give on blogs etc., I tend to forget that it will send repeated emails--wrestling the idea I'm working on into shape, making sure it won't be misunderstood etc., seems too important at the time.