With the right infrastructure, 12 miles is about a 45-50 minute ride, for what it's worth. When I commuted from Santa Monica to El Segundo it was 13 miles and the bike averaged ~5 minutes slower than car (I was in the best shape of my life and loved starting the day that way, to boot.)

At lot of that depends on where you live. Southern California has a pretty ideal climate. I'm in Austin and I can manage my 7 mile commute in the summer until the temperature gets above about 102. I'm fortunate that my workplace has a shower.

A 12 mile winter commute in some of the northern states could be pretty dangerous.

I expect it is, but people definitely do it by choice: https://www.frugalwoods.com/2014/11/19/the-ultimate-bike-com...

12 miles through freezing rain or snow is a bit harder, and that's the majority of the year for most in the US.

12mi each way is a fantastic and doable commute if you're in good shape, but if you aren't and want to still reap the benefits, an eBike is fantastic.

Have you considered an e-bike? Don't listen to the bike snobs, they're really quite good at extending the commute range.

12 miles is totally doable. An e-bike can help make it more doable if it's not already doable for you.