Ohhh it depends...I don’t always use garlic - some sauces aren’t officially supposed to have it and sometimes I follow the traditional Italian recipes quite strictly. Also some Italians (or at least some recipes, maybe it’s by region, I don’t know - I can’t remember as it’s been 25 years since I lived there) hold that you shouldn’t mix onion and garlic in a pasta sauce. I don’t follow rules like that slavishly, I’m not a purist by any means, but sometimes I do.
In a typical pasta sauce (which means something I’m just making up) I use 2 at a minimum and sometimes a lot more. It just depends on what we’re in the mood for. In something like a puttanesca I often use 3 or 4 (for a 2 person recipe) because we like it quite punchy. But that’s not made with meat so isn’t actually relevant here.
For a more standard bolognese (which isn’t actually meant to have garlic in it, I don’t think?) made with 450-500g mince I would use 2 if I didn’t want much garlic flavour, but anything up to 4 I guess - I just throw in however much or little I feel like on the day.
For chilli I use more as we like garlic a fair bit of garlic in it (plus more in the accompaniments!) would use maybe 6 to 8 depending on how big they are.