Sometimes if I’m feeling classy I’ll grind the rest and set them aside to make cold brew with later. That’s more forgiving so I do it to use up old, stale beans that I end up with for whatever reasons.
Most of the time I don’t care and I just top off the weight with whatever I’m using next and drink whatever comes out. It’s usually fine, and when it’s not it’s at least novel.
On our trip a few years back we got some simple pastries, sandwich supplies, and snacks from Bonus to save money and I never felt like we were missing out on good food. Even as a discount grocer everything we got from there was super good.