[Imp]

Dont entirely agree, yes aircraft or more of a lottery & hardest arm to use but they can be very powerfull.
Using against a higher Tech force is generally a bad idea but with parity or superiority can be very effective. For sure more effective in numbers unless a low tech force whenthey can still survive long enough to be beneficial.

WWII find it hard to resist all those German toys often find myself buying one good one, time to make hay.
Aaagh yet again damn AI and pesky allied air put an end to those plans, thats the AI nothing clever.

Evaluating points spent on air is not simply a case of points spent vs points killed far more important is information gathered, distraction upset caused. Never had your surprise attack totally ruined by air probably at the cost of several turns setting it up or saved your bacon by spotting their flank move.

Remember its combined arms they can be used to gather info & attack targets on their own away from ground battle but are best off supporting it, hopefully kill something but at least suppress when someone can take advantage of that. Timing you don’t need to just keep sending them in.
As said combined arms they support the ground force but need support themselves, artillery should be targeting AAA, even if not destroyed suppressed AAA helps the planes survive. Always buy planes after arty to simplify this.

Some cases they can be very useful most obvious one that comes to mind.
Air has parity or better, similar or higher EW rating.
Enemy tanks are superior impervious from the front to most of your weapons.
So you need flank shots on enemy tanks which can be very difficult to set up in some locations.
These take time to set up & more than likely is causing losses to your ground force.
Simple save time & men call in the air, if they have the weaponry use them to take out the tank.
If not setup a pass behind it, with a bit of luck you might detect more units & the tank will turn to engage opening it up for your ground forces flank shot.
So what if my plane did not kill it worth every point for creating the opportunity.

Know your enemy before committing to air because its different to artillery but in the right circumstances it can be very effective. The info it gives you on enemy positions alone can be priceless especially if your force is not mobile so you have some advance warning.