I'm with the 3 days for nominations and 7 for voting.
We can afford being exclusive with the nominations, and people that REALLY want the job need to prepare and campaign before-hand, that's how it works anyway, that way you have 3 days to reconsider going forward or not, people that really want the job will advance in the 1st day anyway, it's a better dynamic to the campaign that people are invited to run beforehand or have 3 days to show they're actually active enough to take the responsibility.
We cannot afford exclusion for our "oh so vast" ecclesia. 7 days is sensible (am I using the right word?), it allows all kinds of people to participate. As Lindisfarne pointed out, there's people who don't have time to check the forums that often, what usually happens is that people are told to vote through various means and purposes (yes, that's what I mean), 7 days allows less rushing and people can actually read the candidate's campaigns instead of taking 2min to vote.
This is STILL 10 days for the process and is far more sensible than only 5 days voting.