Assuming you are talking about in/outs and if you have two coaches...
Coach A stands near the mound with a catcher and hits OF fungo's to all OF's for throws to 2B and 3B. IF's take turns taking throws @ their appropriate base. Throws to 2B are relayed to 3B so that all throws back to catcher go behind coach A hitting fungo's. Concurrently, coach B stands near home plate with a second catcher and hits ground balls at varying depths to first basemen who throw back to catcher. Then, Coach A hits a round to OF to throw home. First basemen rotate handling of cutoff duties (with catcher lining them up). Then, coach A moves back to home plate to give IF standard reps on plays to first, turning two, do-or-dies. Coach B makes his way to outfield sideline to hit more reps to OF's who congregate in deep center.
This gives everyone plenty of reps for most types of plays in a short, organized timeframe with no one standing around at any time.