I always run my pages through validation. Perhaps it is just my perfectionist traits but I feel it is important.
I have often found that even if you show 50 errors, always begin at the top and correct the 1st error, then re-check, many times one error will generate more errors. I did have one new design show 40 some errors and once I fixed the 1st one, it cleaned them all up.
As far as the reporting, if you use Dreamweaver, the line #'s will match up making it easy to locate the bad coding. And you also can tick the "Clean up with html tidy" and it will generate clean code below the errors, just cut and paste the result.
This is especially hand when you are doing an unordered or ordered list that has multiple breaks. ie topic, sub topic, sub-sub topic. That function has saved me tons of time in error chasing.
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"People who are unable to motivate themselves must be content with mediocrity." ~Andrew Carnegie~