I have looked into this in some detail doing deployment studies for wireless HART instruments (industrial processing plant gear) which can talk to a base station or store and forward for a friend.

So depending whether you want broadcast or point to point, or in between, performance is dominated by "pinch points" which is such an obvious term that I wont describe it.

This means that a groups situation in this context could be dramatically improved by a unit or two in a balloon or drone above the group or similar.

I suspect in practice when deployed and medium sized groups use these that a "signals master" or two will have primary responsibiliy to maintain such nodes to keep effective comms up and might use kites, balloons, drones, terrain, whatever and a particular set of skills and equipment would develop.

Also, if any given unit can impose a "cost" relative to business, amount of battery used etc then self levelling and incentive to be terser with messaging can occur. Lets face it, when you are down to 3 bits a second the use of emoticons will drop off pretty quickly.