Much depends on the scale of conflict you are trying to duplicate. Are the rules meant to represent a brigade or wing or army level action? This will reflect the amount of detail you may want for shooting, combat, and combat resolution.
Add to this, determining a winner may not be the result of accumulated losses, but also the commanders willingness to reach a result. Hastenbeck (1757) is classic as both sides thought they lost the battle.
More often than not, generals relied on information relayed from their subordinates and based their decisions to send reinforcements, hold or withdraw.
Moving battalions independently is fine for a brigade level game, but increasing the number of battalions will likely increase the chance of having an unfinished game. Possibly moving groups of brigades in formation might optimize your time.
We enjoy SYW campaigns or have battles which involve preliminary skirmishes before en eventual deployment. We also make use of grand tactical maps which allow us to shift positions to bring a battle elsewhere over a large area.
Fredrick made use of turning maneuvers to flank enemy positions; Leuthen and Rossbach are classic. Reproducing this on the table would only increase unnecessarily the amount of time needed to complete a battle. The grand-tactical map helps reducing the time need to shift troops and make decisions.
Cheers,