It is very possible to rack up million plus scores with colonial troops and alcatraz, I know, I have been doing it now for several weeks, I have the max combat bonuses and started to auto battle about 5 weeks ago as I was not managing to get the best from the resources, even when I do not battles every day, I am scoring 1 million points per week, nobody can touch that sort or score in my neighbourhood, if someone appears to be battling for several hours, it might be that they fight a group if battles all at once and then wait for the units to heal and then fight another group of battles, it can take from 24 minutes to 4 hours for a unit to heal to full strength. You do tend to suffer more damage with auto battle, however, this is offset by the fact that you can also fight a greater number of battles in a given time - approximately 6 times as many