Flanking an enemy is often a luxury. You only do it when your positive that your at a standoff where you and your enemy are relatively evenly matched. If your stronger then the enemy then your center line will plow through the enemy before the flanks can pull up (because they have a longer distance to go), and that can spell all types of trouble.
Umm, the forces are balanced in overall strength, in that the units are carefully chose for each role. The numbers are even, and the battle have been purposely designed to last long, flanks are purely for support and emergency contingency. I know what you mean, I study this stuff ( after all I where I wan to go in life is Military Science and become Staff Officer ). Prime example, Battle of Marathon.
But if your center line is weaker then the enemy then while your trying to flank the enemy will charge into the center line, plow through it, and eliminate the enemies strong units before the flanks can get back to the fight.
Not necessarily, usually use units that can for a lack of a better term "slug it out,"
The Battle of Marathon is a great example for what we are discussing here.
I prefer an army operating as a very large entity when possible.
I can see why, you are right in that too divided is not good. However, through my study of military theory, military science, of the great commanders, rulers, game theory, strategic studies etc. A force with the
teamwork of an entity, but are capable of acting as separate forces is prime. However, concentrate as 1 is asking for disaster, no preparation, no setup, no contingency plan, no wide-field command and control, etc. You might have prep, a bit of command and control and setup, but contingency is usually the key. Also "All Wars is based upon deception,", hard to do effectively with one unit, unless the enemy is a complete idiot. And you always want to divide the enemy SKILLFULLY not spreading you army like thin butter.
Here is something, a nugget
When ten times the enemy's strength, surround him;
Five times, attack him;
*alternatively, alarm him from font, surprise from rear, create uproar in east, and strike in west;
Equal then engage;
Weaker then prepare contingency so you are able to withdraw;
And if everything else is unequal, be able to elude the enemy.
NOT TO BE TAKEN LITERALLY WORD FOR WORD,
it is a summary of a few good points in the Art of War.
There are other aspects, I won't bore you with or type right now, but these are the very very basic.
Double, then divide him;