Re: Mass Combat System and Archery Units
Keep in mind that if you're firing more than a couple of hexes away, it's pretty long range. Depending on the scale you use, firing more than one or two hexes away might not be reasonable for muscle-powered missile fire.
That said, missile fire was rarely decisive in combat until the end of the 19th/beginning of the 20th century. Even into WWI, common wisdom in military circles was that fixed bayonets and martial spirit were what won battles. It took a generation of Europe's young men being thrown into the meat grinder to get the idea across that you just don't charge machine-guns.
Tactically speaking, if your troops are armed with ranged and melee weapons, the ranged weapons are just there for one attack before steel meets steel. If you have troops that are armed only with missile weapons, they should hang back and harass the enemy, keep them from flanking friendly units, keep them from taking a breather and regrouping, but unless they're purpose built to dish out some seriously accurate and damaging ranged attacks, they're just a sideshow.