I'm 35 miles away from work. On the days I cycle (2 per week), I drive 10 miles to the end of our bike trail and cycle the remaining 25. It's mostly flat and takes about 1-1/2 hr each way. Since I don't go to the gym on the days I cycle to work, it works out about the same time. I also save a few minutes because my bike locker is 20 ft from the office door, versus car parking lot blocks away. We do have a locker room with showers.
No worries about narrow roads and little shoulders since most of my trip is on a bike path. Biggest obstacle I have is the wildlife (turkeys, rabbits, squirrels, deer, snakes) and innattentive joggers with headphones.
If I need to work late into the evening or something comes up I can always hop on public transit to get back to my car. I found it essential to have a backup plan to get home in case something happens (mechanical, weather, work, family emergency, or ???) that prevented me from cycling home.