does anyone else break their workouts up?

higgins8283801

I am a busy mom, with a husband who is deployed. My kids play competitive sports and I work and they start school back up soon. I don't have the time for long workout. I just don't.
I have been breaking them up. Doing 20 minutes here and there until I get the total number of minutes I would like.
Am I burning the same amount of calories had I just done a 45 minute workout or am I screwing myself out of potential burn?

I just don't seem to have the time to do one big stretch.