Realistic Artillery Management - FOO Rule

[Imp]

Cant help with further info but makes sense. I would say dont give battery area restrictions rather define patterns as in
1)all fire at 1 hex
2)fire in a star around centre hex
--- * -- *

* - Target - *

--- * -- *

3)Fire in a line any axis just straight
All guns must follow same spacing so adj or 1 or 2hexes apart
Other possibilities are
4) Staggered line 1 forward 2 back
5) Cluster similar to 2 all placements must be adj to 2 other spots so tighter than 2 but loser than 1.

Thinking about as write probably say a line or any symetrical pattern in a area upto 300m

As you say I am sure capable of directing 2 but that is probably the limit. To call in I would think he gives location & dispersal pattern then corrects, fits within game turn timeframe to 2 targets info yes 6 no.
Could be worth putting a shout out for someone who has served in arty as I am sure modern will use much the same or with GPS may actually control less to bring in on specific spot if talking likes of MLRS