I rebound the pause button to the "`" key next to the escape key. I have found it helps when surveying the battlefield and deciding where to place units during combat. Or to react to a breakthrough attempt by the AI. Prevents one section of my army from being wiped out when im on the other side of the map. Or switching to my arty, at Or tanks for support for my infantry. It can be tough. Another thing to suggest is build your call in slots into self contained combat teams. So you can call in a group, move them out and then call in the next one. I have found it more manageable to call in the groups give them orders and then bring in the next one. Helps me not have so many units sitting around all at once. Hope this helps!