The phrase 'mostly prone' is grammatically correct and can be used in written English.
It means to be inclined or likely to do something. Example: "She was mostly prone to taking risks, which often got her into trouble."
The crowd of several hundred people filling the mosque in the building that also houses the offices of Al-Khoei Foundation was mostly sympathetic, prone to dismiss the criticism from American senators and other officials that Mr. Maliki should be replaced.
Harirampur is situated about 86 km away from Dhaka, the capital of Bangladesh and located on the mostly erosion prone area of the mighty river Padma.
Look, I don't want to ruin your view of the Republican party – a party famed for their all-inclusive views on sexuality, immigration and free will – but the reality is the people who comprise it are mostly gaffe-prone, insensitive and misinformed.
Developing countries in the drylands are mostly drought-prone.
The multimeric protein GroEL folds 10%to15%5% of slow-folding proteins, which are mostly aggregation-prone [ 30, 31].
Consequently HR is an essentially error-free repair pathway whereas NHEJ is mostly error-prone and generates mutations.
The latter, such as the canonical non-homologous end-joining (C-NHEJ), the single strand annealing and the micro-homology end-joining DNA repair pathways are mostly error-prone [ 11, 12].
These activities are error prone and mostly manual.
But mostly, rentism will be prone to underemployment and stagnation, because the economy requires consumers and the jobless masses can't afford to consume.
Such a microstructure is highly resistant against dislocation slip upon cycling, while microstructures annealed for longer times and showing mostly recrystallized grains were prone to dislocation slip, particularly as the grain size exceeds 200 nm.
