Generals and admirals have lots of skills, but knowing how to actually command troops in combat is often not one of them. Warfare is a competitive exercise, and the losers often die. Given the stakes, you would think that military commanders would put a lot of emphasis on learning and practicing "battle command" skills. It doesn't work that way. For example, the U.S. Army has dozens of electronic wargaming facilities ("Constructive Training Systems" in milspeak.) These wargames allow commanders, subordinates and their staffs to play a computer simulation that accurately uses military equipment to carry out a military operation. The army has many different versions of these wargames, many of them portable, for units from battalion to theater level. Basically, these wargames are networked computers equipped to plug into the networks commanders would use in combat. The simulation software either uses artificial intelligence to provide an "enemy", or human "Red Force" commanders.
While this appears similar to some commercial wargames (where it's mainly about winning), the army versions are actually quite different. While a commander (and his staff) can "win" or "lose" a battle, that is not the main point of these exercises. The primary purpose of these Constructive Training Exercises is to make sure all the people in the headquarters know their jobs, and can carry out those jobs efficiently with the many other people they will have to work with in combat. Thus these wargames are a simulation process, more than actual combat. Actually, some of the things headquarters people will be doing, like coordinating air or artillery strikes, or planning attacks by infantry or tank units, will involve actual combat. But to bring off any of these operations successfully requires that communications, maintenance, supply and other specialists do their jobs as well. In the navy, training all the parts of the crew to do their jobs well, and in coordination with everyone else, is considered far more important (and often to the exclusion of) than competitive wargames.
The Constructive Training Systems allow brigade staffs to test themselves several times a year, and smaller units, or groups of troops, as often as they like. This is particularly useful when there are new procedures, new equipment, new enemies or new tactics involved. Best to practice with the computer version of the battlefield, before you do it with real people and ammunition.
But the big problem is an institutional reluctance to, well, compete. Part of this is the fear that some officers, thought to be very promising, will crash and burn if confronted with a determined opponent in a simulated battle. This has happened, and the military custom is to avoid this sort of thing. Save failure for actual combat. This is a hard habit to lose. Typically there are a lot of people killed in the first battles of a war, because commanders had little experience running an actual battle. But there has been growing pressure to change. Partly it's a generational thing. Since the 1970s, there have been more and more commercial wargames on contemporary situations, and these have been very popular with junior officers (and a lot of the troops), but less so with the senior folks. Moreover, not all junior officers cared for wargaming out battles they might actually encounter in the future. The manual (and difficult to use) wargames of the 1970s have given way to computerized ones, which are much easier to use, and more officers use them. The military, as an institution, is under pressure to let commanders officially use wargames competitively, with another officer commanding the enemy forces, with both of them under orders to win at any cost.
Another problem area is the search for a wargame that will combine those used by the army, navy, and air force. The army and marines often use the same sims, at least while dealing with ground combat. But the navy and air force operate in a different environment, and when they have to account for what the army is up to, often use sims that have a different take on land warfare. This causes problems when all the services have to operate together, and efforts to resolve these differences continue.