This is now live! Thanks for your patience.
When I came to check out the discussion here, it was nice to see good support - y'all have an active site and I know that you likely get a good amount of content that does need to be closed. As such, I felt that y'all were likely going to fall into needing this change less because you didn't have sufficient voters and more because there was workload that could be lightened by reducing the number of participants in the process.
And that seems to be the case. It seems like, you end up closing about 100-200 questions per month which, while not huge is still reasonably large. The first thing I look at is how many of the close review actions actually get handled on a monthly basis. Essentially, if a question gets a flag or close vote, what is the likelihood that the question will actually get closed.
I'll point out that the top of the vertical axis is 90, which means it's not quite as rosy as it might seem on first glance. Essentially, y'all do a decently good job at handling these - while you've been down in the mid-sixties in the past, recently you've been in the 70-80% completed range:
Currently, the mods here are doing slightly more of the closing (likely with some votes cast by community members) and have been since the 2021 election - I'm guessing that election made moderators out of some of the more active reviewers, which may explain the dip.
I was curious about why the trend over the last year is to have fewer posts being closed. It's certainly possible that you've had fewer questions asked, so less to do but the correlation with the election left me slightly concerned that the elected mods might not be raising the first close votes they may have in the past. But it seems that you have, in fact, had fewer questions asked as time has passed - here's the questions asked:
So, all seems on par, though usually a decrease in questions asked would be concerning, it's not the subject of this post, so I'll leave that for another day.
On a whole, it seemed that enabling three vote close/reopen would be a worthwhile change here, so I've enabled it. Please do let me know if you start experiencing any issues. I did check in with the mods before changing the site setting to make certain that the concerns in Mast's answer were well in hand - and it seems that they are, and aren't of as much concern now.
I'll check in in a few months but I likely won't update this unless there's something particularly concerning - as such, consider this the new normal. We can always push you back up to 5 if things change in the future, so don't hesitate to ask.