NPCs shouldn’t be fully fledged out characters. They are many to be encouragement for the party to improv/ roleplay. If they are hard coded with weakness or aspirations you can’t adapt as the DM/GM. If this is a plot centered NPC such as a patron or BBEG, sure.

The most memorable NPCs either work as a foil for humor or cause a split in the parties loyalties/morality. Too do those things, you need to adapt to a moment.

This seems a little more detailed than I usually go with.

I’m happy cribbing from Fate. Every NPC has a high concept (eg: royal assassin, gig worker delivery man) and Trouble (eg: drinking problem, haunted by well meaning but overbearing grandfather)

If they need more flesh, they can pick up more aspects or goals.

This is a cool way to sketch out npcs, I like the examples given. But it could be expanded to be even more thorough, resulting in more complete npcs.