I cut open most of mine, but not all. I have an oil filter cutter that I bought from Jegs a long time ago. Before that, when I used a Dremel or hacksaw, I barely ever cut any open. Now it's just like opening a can of veggies!
Yes, I cut open all of mine with a Longacre filter cutter. But I don't surgically inspect the element unless I have some concern about abnormal operating conditions over the last OCI.
I cut anything I'm testing and trying out, or anything that I don't recall having been posted on here recently. You can learn a lot even if there are not any visible "defects".
When my only way of cutting them involved a hacksaw or sawzall, I didn't cut too many. Now that I have a filter cutter I cut all of them open since it only takes a few seconds to do so.
I'm always curious to see what is inside, both good and bad.