The phrase "are mostly free to" is correct and usable in written English.
It can be used to indicate that individuals have a significant degree of freedom or choice in a particular context.
Example: "Employees are mostly free to choose their own working hours, as long as they meet their deadlines."
Alternatives: "are largely allowed to" or "have considerable freedom to".
Americans are mostly free to pursue happiness however they choose with little interference from the state.
Arsenal, Manchester City and Chelsea have already played Under-21 matches at their first-team stadiums and the fixtures are mostly free to enter.
Exchange rates are mostly free to adjust to close global imbalances, reducing the need for deflation in deficit economies to restore competitiveness.
But the tribes are mostly free to decide such matters among themselves, which they do, remarkably harmoniously, through jirgas and riwaj tribal customary law.
Owners of destroyed homes are mostly free to rebuild them on the same spot, although new floodplain maps have expanded the areas that require houses to be elevated, and, in some of the most vulnerable areas, raised on thirteen-foot stilts.
Players are mostly free to decide the classes, abilities, and statistics of their characters.
In America, where they are in the deepest trouble, the person often blamed is Craig Newmark, the founder of Craigslist, a network of classified-advertising websites that is mostly free to use.
The {111} solid solid interface was cusp-oriented while the surface orientations of the Cu-rich and Ag-rich phases at the tri-junction were mostly free to vary.
These "guests" were mostly free to move about the house, Bochove said, but were prepared to scramble to the attic if the Germans came.
This law was still on the books despite the Supreme Court decision in Lawrence v. Kansas, which said that individuals were mostly free to do sex in private.
Because Britain's big London galleries as well as regional museums are mostly free, they have to generate income from exhibitions – for which they charge plenty.
