Looks like it, ya. The ceremony is full of symbolism too. Here is just an exerpt I found on it:

"The Tomb Guard marches exactly 21 steps down the black mat behind the Tomb, turns, faces east for 21 seconds, turns and faces north for 21 seconds, then takes 21 steps down the mat and repeats the process.  (The number 21 symbolizes the highest military honor that can be bestowed, the 21-gun salute.) Next, the Sentinel executes a sharp "shoulder-arms" movement to place the weapon on the shoulder closest to the visitors, signifying that he or she stands between the Tomb and any possible threat."

https://www.arlingtoncemetery.mil/explore/changing-of-the-guard

What’s up with the parentheses? I’ve never seen anyone make an entire comment in parentheses and there are two on this same post.

Nearly uninterrupted. There are very few times they aren't out there, and it's pretty much only due to hurricane force winds. Otherwise, it's 24/7.