ORIGINAL: Lowpe
Recon is only a point to point mission. To get recon on enemy LCU arcs do not apply, only clicking on the specific hex you want to recon.
For naval search/ASW planes only fly the arc sectors.
Alfred, once again many thanks.

I have been assigning arcs to recon squadrons all the time. I don't know where I first assumed they use them.[&:]
According to the manual, a Recon squadron will at most fly 4 planes in a day?
If the target of a Recon mission is Commanders Discretion, is the targeting per the description of automatic combat targeting in the manual?
"Yes"[;)]
The Recon Mission is considered to be an Offensive Mission and as such, s.7.2.1.7.1 of the manual "applies". However, what you need to bear in mind is that excluding recon, all the other offensive missions are active missions whereas recon is a passive mission. Those active missions
raison d'etre is to inflict damage and hence under commander discretion they are evaluating which of the known targets are most worthwhile to attack. The passive recon mission, which is a point to point mission, has very little to base its evaluation on. It really only has the MDL of bases to work with as all bases have an automatic MDL of 1. Under commander discretion the recon unit will not fly to a non base location (which has a MDL of 0) just on spec to see if there is something there.
In practical terms, if you set a recon unit to commanders discretion, the same base will continue to be reconnoitred. You won't select the base and you may end up with more info than you need on a base which is not high on your list of priorities. Other than saving on clicks, there is little to recommend relying upon commanders discretion for a recon air unit.
As to the number of recon planes flying, yes the maximum will be 4 per unit, all to the same base/location in that turn. This is why it makes sense to breakdown recon units. Of course breaking down units will see an increase in pilot and airframe fatigue as the utilisation rate will be higher and consequently less time for de facto resting to occur.
Alfred