There’s a cool little trick to help get everyone the tower Achievement by day 10.
After you’ve figured out your path and have set markers, give everyone a 2 a day tower limit. When you place the first tower on the 2nd day do a roll call for those that haven’t done any and give them dibs. Use whoever to fill them up if need be. So on day 4, for example you would roll call for those that have 6 or less first. Then zero since reset, then 1 since reset, then just fill them up.
Continue doing this every day at reset and by day 10 everyone should have the 20 tower Achievement and will have equally helped to get the alliance achievement: