Maybe somebody find this post useful.
This test were performed with a Soviet recon planes SB-2 in clear weather.
Here are our recon targets:

this is WRONG recon settings, just to show what results it will produce:

i specifically set fly path not to go over a units and to get only pure recon results
also i changed loadout to 3x mid lvl camera
as by default there are none
Its a poor result, 5 hexes with 5-30 recon value, other with 0

Now here is a proper setup if you want to get at least 1 recon value in each of the hexes:
there are 22 hexes where we want to fly recon
So i decided to fly with the following setup:
every day of the week
which gives 7 days * 3 strikes per day = 21 (hexes in theory) which gave 20 hexes checked
and 3 planes (Req AC) to get more recon value, as i was also experimenting with a one plane per strike
All other settings are the same.
Results:
in swamp/light woods there is at least 1 recon value
in clear hexes: 12, 8 , 9 recon value

It means that if you want to cover more hexes - you should increase strikes count OR/AND days when recon is flying
while increasing planes count - increases quality of a recon
For example this 2 setups will work the same.
1. 3 days per week with 7 strikes per day
2. 7 days per week with 3 strikes per day
Result will be - 21 hexes checked. (unless area for recon was smaller than 21 hexes)
I was testing many more setups with a high level cameras, medium level cameras, different altitudes and so on.
It does not matter in the end. Ops losses and recon results were the same.
But i have to admin that there is difference if planes do not have any cameras equipped. Recon will be much worse. So remember to check planes loadout before flying recon.
Also i was even asking for a 12 planes per strike but still did not manage to identity unit type in non clear hexes. And for a clear hexes it was enough to have 3 SB-2 with cameras per strike.