Yes indeed. Even in my experience in the Marine Corps, change is an ever present reminder of the passage of time. I noticed that even from the start. As a lieutenant, I left my first unit and noted how most of the SNCOs had moved on and that Marines that had checked in as PFCs (in the Marine Corps and E-2) were now corporals. I visited that unit a few years later and didn't know anyone!
Right now I'm struck by the fact that my Marines are closer in age to my elder son (17) than they are to me - by far! The youngest Marines are 1 year older and the average is probably only 4 years older. By way of contrast, I'm older than them by an average of 21 years! Just looking at the command board is another indicator of this. Our command board has pictures of the CO, SgtMaj, company commanders, and staff heads (for the S-1, S-3, legal team, chaplain, etc.) What I am noticing now is the surprising lack of stars on the National Defense ribbons people are wearing. The National Defense Medal is authorized during times of conflict. The fact that it is awarded as soon as you join gives it the moniker the "Fire Watch Ribbon", The latest time period it was authorized was following 9/11 and is still issued to the current day. The previous time period it was issued for (and for which one would have a star on the ribbon or medal) was Desert Storm and the inclusive dates were August 2, 1990 - November 30, 1995. As I went to boot camp in Feb of 1995, I rate it and so have the star. On the rack below, it is second row, second from the right (red on ends yellow in middle).
So what this means is that the majority of people who are in senior positions in this and most battalions joined after November of 1995 - even the first sergeants!
Just another reminder of time gone by! And pretty soon, my star will be gone from the board as well! :o