Even if I’m checking a bag, I always bring essentials – which includes nightclothes, toiletries, and a change or tomorrow – in my carryon.
I guess I don’t do car trips – I don’t get the idea of “pack it so I can leave some of it in the car”. My goal is to pack it so it’s easy to carry all of it. I do often re-pack after I check into a hotel, re-using my smaller carryon item as a dayback or large purse, which means I remove the aforementioned toiletries, nightclothes, etc. and replace them with whatever I want to have with me during the day.