On public transit and airplanes, definitely. I used to get colds all the time when traveling; I don't anymore. I think part of that is down to improvements in air filtration, but part of it is masking.
In some shops, but not all. Mostly in shops that have a lot of people in at once, and shops that request it. I don't mask if I'm going to the corner store to pick up some beer; I do mask at the grocery store that has a sign requesting it.
Never for outdoor events. This might be different if I lived in a different city; a friend of mine who lives in the LA area does mask for crowded outdoor events.
Also, doctor's offices and a few other places require it.
(Curious observation: On transit, I'm not usually the only person with a mask on, but I'm often the only non-Asian person with a mask on.)
Yep, airport for sure. I used to get sick everytime I flew. Not anymore and in hindsight it seems stupid that I never masked at the airport before. And doctor's office if it's my primary care or urgent care. Not much of a need for a mask at the dermatologist. Basically if I'm somewhere there's a fuck load of contagious people.
Recently though, the air quality has been so bad from the wild fires up north that I've worn a mask while out. I came home one day from coughing like crazy and my throat was sore. I thought I was getting sick until I put two and two together about the thick haze of wildfire smog. Masked up until the AQI went back down and saved myself some discomfort.
Yeah, this is pretty much my standard now too. I was in hospital for a day surgery recently and was more than a little taken aback at the fact that I was one of the only people masking.