Working out too much is almost worse than working out too little. Don't be fooled, more does not equal more in terms of duration and frequency. 
The key to working out effectively is to find the proper balance of work + rest. 
You may need to experiment to find out what is right for you. Everybody is different. 
If a shorter workout means that you will put more effort in to it, then yes, it will be more effective than a longer one. The time it takes to complete a workout should be less important than the intensity, passion and drive put into it.