Word echoes, how I hate them.
When I started writing, I had no idea I had a problem with inadvertently repeating words, until it was gently pointed out to me by my peers on Youwriteon. I was appalled when I realized just how bad I was - entirely capable of using the same word three times in the space of ten lines. There's also the common variant of starting successive sentences with 'He' or 'She' - one YWOer started thirteen sentences this way, in one paragraph.
I an still prey to word echoes, but constantly check and re-check in order to remove them.
Indeed, I'm now so aware of it that I notice repeats in published books - John Le Carré writing 'it occurred to her' in successive paragraphs in The Little Drummer Girl, for instance. So I reckoned I'd got it licked, until I read this excellent article, The Ten Mistakes. Oh my God, 'There was'...I'd got 61 of them in 51,000 words, including 'There was a pause' and 'There was a silence' really close together.
It never ends.