Roughly speaking, for a 11 mile cross town commute
Leave at 6.50 in at 7.30 leave at 4.00 home at 5.00
Leave at 7.10 in at 8.00 leave at 4.15 home at 5.30
Leave at 9.10 in at 10.00 leave at 6.30 home at 7.15
Sometimes its quicker, sometimes slower. On a quiet day, its doable in 25-30 mins. Generally the further away from peak times, the faster it is. You can add at least 30mins each way if I leave at peak or I use the train. If I get the bus you can add an hour each way. But as generally have to go somewhere off route on the way home, I usually take the car. If I have to drop/collect a child you can add 15/20mins on that leg. Personally anything over 40mins for a commute oneway feels too long for a regular commute. Though rarely have I ever acheived that in a job.