What he’s referring to in that video is called “bullet setback”. In another thread I compiled a few videos on the subject. In particular, watch the first one from Sage Dynamics which includes some measurements with a caliper.
Every time a round is chambered, you may get some setback. It’s not usually until you’ve chambered it a bunch that you see setback, but “bunch” varies from firearm to firearm and bullet to bullet.
Before COVID, my carry pistols normally only came unloaded at the range when practicing, or a clean/check every month or two. I kept that habit to reduce administrative handling. I would take that once-chambered round and set it aside and when I had enough that would go in a mag that got fired at the range.
After COVID I have been dry-firing a lot more and as a result have needed to empty the firearm more often. But I also don’t want to be so cavalier about shooting my defensive ammo which is now super expensive if you can even find it all. So now I mark the case with a marker every time it gets unloaded and after 5 chamberings I set it aside instead of just 1 chambering.
I don’t think the amount of time (days, weeks, months) matters unless it’s been in there a long time (like over a year) or exposed to the elements for some reason. It is the chambering that does the damage.