Is working long hours a sign of dedication or inefficiency?

in my view, as i am working in office, people create a hipe of working late hrs in 90% of cases. Actually fruitful work is only in office working hrs only. above that and any one is working is it is in my sense extra and showing that how hard that work is and how hard they are working.

To be frank there is no work  99% in late hrs, if we plan accordingly. but no one plan like that every work people do at the last moment with "emergency / urgent" as tags.

being in top position will not enhance work but shows us the way to escape

In my opninon it is both the things.

As in now i m doing late hours for enhancing my knoweldge after the office hours.

As in during the office hours i am having my own sets of deliverables & during that time i cant experiment with the things.So as a result thereof i am doing late hours.

At the same point of time if i am not clear about any work and before doing that i need to do some research work then it is ineffieceny in my part and to complete the work in the required time frame i need to do late hours.  

The working of long hour is necessary during the intial stage of carrier.

As you become inhabited with your profile time duration is not relevant  but what is the subject matter is relevant