As the Major points out, these things run in cycles. I served from 1965 to 1968, including a year in Vietnam. I‘m working from memory here, but I think my awards were as follows:
Expert Rifleman badge - M14
National Service Medal - awarded to all upon completion of a certain period of active duty - six months or a year, I can‘t remember for sure. Some believed it was for serving six months without contracting a social disease, but I‘m fairly certain that isn‘t true.
Good Conduct Medal - awarded to all who manage not to run afoul of the military justice system.
Vietnam Service Medal - the basic ‘I was there‘ medal. Similar medals have been awarded for service in combat zones for a long time.
Vietnam Campaign Medal - with two clusters. In the Army this medal shows your service in designated campaigns. In my case it was pre-Tet and post-Tet. Campaign medals date back at least to WW2 and probably beyond.
That‘s it. Oh, and if I‘d stayed in the Army I could have worn either a MACV patch or 1st Aviation Brigade patch on my right shoulder for the balance of my career. Denotes the unit you were in during your service in a combat zone. I think this is still done.
I believe the awarding of medals by the gross started with the Air Corps and continued in the Air Force and Army, especially where Air Medals and Bronze Stars are concerned. Grenada marked one of the worst cases of medalitis. I think things have been improving -- but Major Baker will be more conversant of that than I am.
Jim