The Covert's utter failure to make smart strategic decisions when attacked by the lake monster, instead insisting on holding their ground, refusing to use a simple tactical withdrawal, and failing to organize any kind of cohesive professional response can be surprising… until you realize this is likely a reflection of their being religious fanatics devoted to a stubborn ideal on the wrong end of the Soldier vs. Warrior spectrum, and likely explain how Gideon was able to eliminate the previous Covert with his professional Remnant forces, even though stormtroopers are usually infamous as poor henchman.
Din not suffering their flaws is also explained by his backstory of having worked as a criminal enforcer for a time and simply having gained experience in practical combat against superior forces (including against extremely large animals) repeatedly.
We see a child get his first Mandalorian helmet and swear never to remove it but what happens when his head grows?
The Armorer forges a new helmet for him, and he puts on the new one in private.
He's old enough he probably won't grow much more — but yes, he could get a new helmet if his old one was too small, damaged, or otherwise needed replacement.
But what happens when he (or anyone else) needs a haircut — I mean, we don't see Mandalorians with hair spilling out from their helmets... except for that boy?
Worth noting that, according to the first season, droids don't count. And we see in The Clone Wars that droids that can give someone a shaved head exist. Even in real life, it's not hard for someone who favors a buzz cut or a shaved head to do their own hair cuts with a clipper.
Din is not comfortable with the droid seeing him helmet-less. I think he DIYs his own haircuts. Should his haircut then be rougher than it is? Yeah, but Rule of Glamorous. He's man of many skills, though, and with years of practice he could justifiably be pretty good at it.
