Regarding masking in cars - best practice for good mask wearing is to put it on, ensure a good fit, then leave it on until you're done with it. If someone is running errands, it's better to just put leave it on instead of donning and doffing it repeatedly, making it more likely to cross contaminate or ruin the fit.
If we were talking about alcohol consumption "slow down and think about it" absolutely makes sense: I might be having fun in my 20s binge drinking but there are very real negative consequences of that behavior long term.
But in the scenario where someone is in their car with their mask on I'm missing the "slow down and think about it" rationale. (Again, I've heard the talking points on this, so I'm looking more for a real answer).