Evaluating productivity in Investment Banking Environment

I'm a first year investment banking analyst at a boutique investment bank. There are only a few analysts in the department. Basically we support all the deals of all the senior bankers. As analysts, we are asked to provide timesheet-hours you spend on projects and your projection for next week.

There is an analyst who joined a year before me. He takes forever to do everything and he will disappear during the working hours for a few hours if the core senior bankers are not around and come back to the office really late to send out email like 3, 4 AM in the morning all the time and put out those ridiculous long hours on the timesheet. And everyone seems to buy that and think he's the hardest working person ever. Do people actually value productivity? When I'm in the office, I always work like a mad man because I don't want to stay too late or go in too early in the office. We do pretty much the same thing, but my hours on my timesheet are usually 20 hours less than his.

I want to say something, but I don't want that to come out the wrong way and bite me in the ass. But I'm really frustrated that he's playing this game. You guys have any comments or suggestions? Much appreciated!