8 is a lot. I think 3 per round is a good balance...unless you are throwing an ED in there. Doing 3 for R1 last year was tough, talking with folks they said that by the time you get to #5 you are starting to get burned out and quality starts to slip a little.
I agree, 8 is way too much. Go for 3 and select those schools have the best fit for you (realistic to get in, specializations you plan to do, quality of profs etc.)