The phrase "a final factor" is correct and usable in written English.
It can be used when discussing the last or most important element that contributes to a decision or outcome.
Example: "After considering all the variables, the cost of the project became a final factor in our decision-making process."
Alternatives: "a crucial element" or "a determining factor".
There's a final factor that should be appreciated, too.
There is a final factor that could play in his favour.
A final factor is the shift toward protectionism and all the regulatory uncertainty that brings with it.
A final factor in favor of hydrogen fuel cell vehicles is that they can be refueled in a much shorter time than battery-run electric vehicles.
A final factor likely to aggravate tensions is that the heavily-indebted Generalitat has become shut out of the bond markets – an inevitable collateral effect of the Spanish crisis.
A final factor making it difficult to determine which laws apply is the flood of new products and services that the industry offers, as well as the different types of situations in which consumers make mobile payments.
As a result, the final factor solution consisted of 24 items.
In the last days before the crash, the rush to build the railways added a final, lethal factor to the mix.
The "small minority" is the problem, not you.There is a final political factor at work, one founded in a basic psychological need.
A final important factor is whether Friday's missile strike is an one-shot response to Assad's use of chemical weapons or whether it leads to broader military involvement.
And, a final contributing factor is that changing markets and regulations have helped startups raise millions, even billions, of dollars that can fund efforts to change laws, engage experts, and battle incumbents and regulators who stand in their way.
