My tendency when writing is to give every character a name. Even the most minor ones. It says something about a nobleman when he knows every guard and stablehand by name, and it's something I want. So it's never "a guard" - it's always "Sergeant such-and-such".
Another effect that I like is that of the world being populated - there are people in it, and every person has a name, and that means - a life, even if we don't see it. A world where everyone aside from the main characters is "a guard" and "a servant" feels to me like everything around the main characters is theatrical scenery made of cardboard.
I'm a discovery writer, so first time a guard "comes on stage", he gets a name. Next time I need a guard, I pull out that same guy who I've already named. So characters start getting mileage. I don't plan anything for those characters in advance, but over time they do get a life.
My concern is: I often hear complaints with regards to some published works (e.g. A Song of Ice and Fire) about there being "too many characters", "too many names to remember". Now, "a guard" is not a character - he's a prop. "Sergeant such-and-such" is a minor character.
Is that something I need to be concerned about? Are there ways I can mitigate the downsides of having a great many named characters in my novel?