The thing is, those fighters offer a good bit of flexibility, but not an AWESOME amount. There are really only so many places to pop those fighters, and depending on what you’re doing, they will be more or less useful.
If you base fighters at Western Europe, you can protect some coastal territories from invasion, while also strafing territories that are pretty close to Germany. If you base fighters at Norway, you can hit that sea zone northwest of UK that the Allies often use to hold their fleet at early.
But if you base at Western Europe, you cannot hit most of the vital territories like Caucasus, or West Russia, without at least having to base your fighters at, say, Eastern Europe on the following turn. The fighters just don’t have the range.
And if you base at Norway, your fighters are vulnerable to attack, which means that you’d have to keep infantry back from the front lines to protect them. Even if your fighters are not vulnerable to Allied transport attack, they are pretty expensive, and will have a hard time sinking a unified Allied fleet.
This is not to say that a fighter a turn is a bad idea. But I think it better to see which way the Allies try to go before committing to a fighter a turn. If the Allies are gearing up for a KGF, a fighter a turn can be pretty solid. If the Allies are gearing up for a KJF, I would want infantry, artillery, and tanks instead.