Yes Keith one of the reason for getting the case gauge is to monitor case and shoulder length. Now i use a caliper for measuring case length. But with the case gauge i can do both case and shoulder measurements and do it faster.
The second reason i think i need the length gauges. I have three 30/30's and one of them has a chamber has a shoulder that is close to or at factory length. An if i get a couple of cases shot from the other rifles mixed in with the proper length cases. I get cases jammed in the chamber that need to be pushed out by a cleaning rod from the muzzle. I use a magic marker and color the base of the case to show which rifle they go to. But when i clean my brass in the wet tumbler the ink is removed. So i have to chamber each round to see which rifle it belongs to.
I may have to make all of my cases the same shoulder length (close to factory) So i don't have to check each case after cleaning. Even though i will over work a few cases. it would be faster in the long run.
I have several Wilson cartridge gauges, they work fine for me. I also have a Sheridan slot gauge for .458 Socom and it can only be described as magnificent. The advantage of the Sheridan is you can see how the shoulder and neck is fitting in a SAAMI-spec chamber. The Wilson gauges have a step at the back to indicate minimum and maximum allowable headspace length and also a step at the front end for minimum and maximum case trim length.
I have the wilson for 30/30, just one rifle but the chamber is longer than spec. I use feeler gauge on the case gauge to measure the case head protrusion to set the sizing die. Necks never seem to get long. If the shoulder isn't too different, just set for the shortest and check for case web wear. I got a bucket of fired and 6-7 boxes of factory ammo for cases. I case check for 308 as they are autoloaders and it get bad if they aren't correct. None will really check case/neck diameter.
When I had multiple 06's they were kind enough to prefer different brass brands . RP for the 03' , WW for the Rem , and LC for the Savage . Each had a different long or fat shape that wouldn't take the others brass even close enough to force the bolt .
Don't know a thing about case gauges except the one that I had made for a custom 45 S&W to check case length and that's one off duplicate of my chambers so that's not much help .