It's important to understand why you trim a case. Then it becomes obvious. You trim it to keep it from being so long that when you chamber your round the case is so long that it gets pinched down onto the bullet keeping it from releasing during ignition. This causes a big spike in pressure.
I have a set of these and really really like them.....
I've found that many guns I own have way more generous room than saami spec. I have a couple weatherbies and a savage that just plain never need trimming before the brass is shot because they have over .030" extra room beyond saami. One insert works for many calibers. They are a real eye opener and have saved many hours of trimming for me.
Unless you have them please be sure to trim before final loading (after sizing). I personally know a friend that sheared a lug on a bolt because he wasn't trimming. It could have been much worse.