Groups can be used for a number of reasons and a single village can be placed in multiple groups..
I use three types of groups..
Area Groups..
Example.. Groups named K48, K49, K50
As the name suggests villages are placed in these groups based upon their location on the map.. This type of group is most usefull when looking for assault/support vills that are local to the village you have interest in.. In addition they are useful when I am looking to movve resources around from one vill to another..
DEVELOPMENT GROUPS
Example DevA DevB DevT and DevX
DevA is all my villages without academies..
DevB is any village i have with an academy but still needs other buildings produced.
DevT is all my vills that have been completely built, but need troops..
DevX Are all my vills that are completely full..
The DevX group is really useful because once per day, i can go into the Academy and mass mint gold coins from the DevX group.. By doing it this way I know for sure I'm using resources for coin minting that are not needed for building (Since any village needing buildings would be in DevB)
When mass recruiting, I know I can use 100% of resources from DexT for troops, and 50% from devA and DevB
Pre academy villages tend to be building upgrades that take less than an hour each, DevB villages tend to be building the lvl 25-30 upgrades that take 12 hours each.. Thus i can check and update the build queues of the devA group 5-6 times a day and the DevB group once a day..
Village type groups
VTA
VTD
VTS
Thjese groups merely show the type of village specialisation.. VTA - Assault VTD - Defence VTS - scout..
By using these groups I can at a click list ALL my defence vills, or all my assault vills.. This can be very useful in farming, or sending mass support..
___________________________________________________________
ALL my villages thus belong to 3 groups..
For example Hells Ridge... VTA,DevB,K50
The three groups tell me at a glance, hells ridge has an academy, but still has other building to make.. I want it to specalise in assault troops and it is in contenant 50..
_____________________________________________________________
This is how i use use groups,, hope this helps..