There are a few places we visit a lot more than others (favourite pub and kebab shop) and often have a good chat with the owners or the wait staff to the point that we all know names and about each others lives and family and they know our usual orders or want feedback on new menu items.
I'll normally tip 20-30% at those places depending on how much I'm spending in total. It doesn't have to be somewhere we frequent, I tip the same wherever the service has been good.
I'm way more inclined to tip at an independent store than a fast-food chain but thinking about it, I am more likely to also tip at somewhere like Subway, but can't remember tipping at McDonalds - I guess it's that the former has more of a "personally made" aspect to it rather than just buying a product? For the same reason you don't tip the cashier at Walmart ...
I also tip food delivery drivers well, because it feels like they do more work to deliver your food and especially if it is miserable and cold out. We also tip at the bottle recycling because I wouldn't want to do that job and I doubt they get paid a lot.
Right now, there are a lot of people hurting and people's jobs in restaurants can disappear in a flash with the lockdowns, so if you're doing OK and have a good income I think you have a duty not to be stingy.