I only tip when I think they deserve a tip. I tipped the last meal I ate out. Nice person who checked every few minutes if we needed anything else. They kept our drinks from getting empty. The service was worth the tip so they got it. That is what the tip is for. Good service, not any service.
She just walked by and checked. We were not the only table getting that kind of service. She only stopped when she saw a glass getting empty or when she saw we had finished the meal.