My advice (and it's from the heart - left ventrical to be precise), keep both at your study desk! Use Schaum's, and if you need more clarrification on a subject, switch to Campbells!
Why might you need more clarification on a subject? Maybe during Bio 101, you had a hangover when your prof was explaining the hardy weinberg principle - you might want to refer to Campells here.
When not to use the text book? When you know a subject fairly well from your Bio 101/102, and you just need a quick refresher.
If you made a B or an A on a particular Bio Exam - then Schaum's would be great. If you made a C - then refer to your text book if you want, or if you feel the need to do so.
Diversify you review not only between your subject areas, but also within your subject areas!
Hope this helps! Remember - your studying for a different kind of Exam than a prof would give. It's (from what I've heard), mainly a factual exam.
My Main Advice - Just Find SOMETHING - and read it as long as it helps!
Thanks for Reading