Been my experience with bottle neck brass, especially the higher calibers, 270, 308, 30-06, that the brass will lengthen, and not all will lengthen the same, even from the same batch. I never got into hot loads, much prefer accuracy, but for no more trouble than it is, I measure brass, even straight wall pistol brass. A trim die doesn't cost that much and you can check length on several hundred rounds before it gets boring.
To me, the bottom line is that if you're going to do something, do it right, especially in a matter that might result in a loss of life, limb or eyesight, as we used to say.
On a side note, I'm not a big fan of Lee products, but I did get a good deal on one of their new Quick Trims, along with a .223 die. I tried it on a few fired brass I had here, but most had already been trimmed or checked. It seemed to do a good job, I hope it works out.