You're right: it could hurt IF you don't!

I very much prefer you asking "inane" questions than hearing about you in the news.
Now, you could measure your case length with a caliper, compare it with the SAAMI standards and decide if you need to trim.
The reason the Lee trimmer works
only on sized and deprimed cases is because of its design; it is practically foolproof: there is a length gauge for the particular round you want to trim which screws on the cutter face.
At the end of the gauge there is a small hardened rod which goes through the primer flash hole and abuts on the face of the caseholder when the gauging rod/trimmer assembly is inserted in the casemouth.
When the trimmer spins, it cuts all the excess brass on the casemouth and when the rod touches the caseholder, the trimmer cannot cut deeper.
So ALL your cases will be trimmed the same.
Then deburr and chamfer slightly, clean your primer pockets and you're all set.
Good luck!
PP.