For the most part, yes, being a perfectionist is a good thing. It means you make fewer mistakes and generally produce work of a higher quality than those who care less or put in less effort.
The problem comes in when you aren't sure where to draw the line, and end up spending too much time being pedantic and nitpicking and not enough time on the actual nitty-gritty of the work.
Unfortunately the harsh reality is that other people probably aren't nearly as fazed about the logo being in the exact same place on each page as you are, and even though it bugs the heck out of you - it's still not worth spending an hour reformatting your work when the last two pages have yet to be completed.
However, if you are able to manage your time efficiently and you understand what your real priorities are - and ensure that they are done first - you can factor in time for proofreading, re-proofreading and re-re-proofreading till your heart's content.
Spelling errors are my nightmare (if you spot any let me know!), although I've been told some people don't even notice them…
What do you fuss over?