The phrase "mostly of the time" is grammatically correct and can be used in written English.
It means "most of the time" or "usually." Here is an example: "I try to eat healthy, but mostly of the time, I end up snacking on junk food."
As the second of six girls in a family living in Crown Heights, Brooklyn, she described a childhood of trying to keep her head down from a mother whose words, she said, "could tear us up in a minute" and a stepfather who made her "feel afraid mostly all of the time".
Actually it was mostly because of the time, it takes 5 min by car and 25 min on foot /…/…and you are often in a hurry and have to be there ten to eight or something.
It's become an overwhelming task, mostly because of the time it takes to organize the various photos.
It showed that approximately one-third of melanoma patients experienced considerable levels of distress, mostly at the time of diagnosis and following treatment.
When it comes to lying, Politifact finds that only 2% of what Trump says is true, with another 7% "mostly true," for a grand total of saying things that are at least mostly true 9% of the time.
But he was a product of his time, he responded to his zeitgeist, and in comparison to the other mostly European leftists of the time, he was already a warrior, already a fighter.
My Kids Are Seated Five Rows Behind Me! Planes are flying mostly full most of the time thanks to major capacity cuts over the past decade; during peak travel times, empty seats are even harder to come by.
The author of books including "The Vegetarian Epicure," "Love Soup" -- and a filmmaker and faculty member at American Film Institute, while she's at it -- Thomas considers herself "mostly vegan most of the time".
However, in our study, TTE was performed within the first 2 days after admission of the patients and mostly at the time of admission.
