I very much don't like the idea of requiring fewer reviewers in general, for much the same reasons as Joe W mentioned. When people actually edit a post, they tend to put in some effort - they're doing a complex task (editing the text of the post), their name's going on it. But when going through the review queue, and only making a simple yes/no decision, it's very very easy to skim quickly and miss things.
If suggested edits aren't getting reviewed quickly enough, it's because people are not often enough going into the suggested edit queue and doing the reviews.
Here's a post with a pending suggested edit:
And here's what happens when I click edit:
(Screenshots are from another site, since there's nothing in the queue here right now.)
At this point you can cast your one approve/reject vote and see if it's enough to finish the review. You can also "improve edit" or "reject and edit", if you have edits you want to make, and you're willing to make sure the entire post is in a good state after your edit (i.e. that you haven't introduced issues by accepting the suggestions, or that you haven't left issues unaddressed by rejecting the suggestions).