Found 11 stronger alternatives to upgrade your writing.
Almost all the time
Nuance: Nearly always
Stronger than mostly; close to always.
Boring
Mostly, the library is quiet after lunch, except on assembly days.
Better
Almost always, the library is quiet after lunch, except on assembly days.
Most, but not all
Nuance: Generally true
Very clear and common.
Boring
Mostly, the class followed the schedule, but we ran late on Thursday.
Better
For the most part, the class followed the schedule, but we ran late on Thursday.
Most, but not all
Nuance: Main part
Common and clear.
Boring
Mostly, the delays came from the bus being late, not from students being unprepared.
Better
Mainly, the delays came from the bus being late, not from students being unprepared.
Most, but not all (phrase)
Nuance: Mostly
Good for explanations and essays.
Boring
Mostly, our project turned out well because we planned ahead and fixed problems early.
Better
In large part, our project turned out well because we planned ahead and fixed problems early.
Most, but not all (formal-ish)
Nuance: Mostly
A bit more formal than mainly.
Boring
Mostly, the fundraiser succeeded because families donated at the games.
Better
Largely, the fundraiser succeeded because families donated at the games.
Overall / generally
Nuance: Overall
Means overall; more about the big picture than every detail.
Boring
Mostly, the plan worked, but we had to adjust one step after the first trial.
Better
On the whole, the plan worked, but we had to adjust one step after the first trial.
Most, but not all (formal phrase)
Nuance: Mostly
Formal; good for essays.
Boring
Mostly, the class improved this semester, although a few students still struggled with longer passages.
Better
To a large extent, the class improved this semester, although a few students still struggled with longer passages.
Overall (idiom)
Nuance: Overall
Idiomatic; means generally/overall.
Boring
Mostly, the group stayed focused, even when the room got noisy.
Better
By and large, the group stayed focused, even when the room got noisy.
Mainly (formal)
Nuance: Mainly
Formal; slightly old-fashioned.
Boring
Mostly, the noise came from the hallway, so the teacher closed the door.
Better
Chiefly, the noise came from the hallway, so the teacher closed the door.
Mostly (formal)
Nuance: Mostly
Formal; good for data/analysis.
Boring
Mostly, the budget was spent on supplies, with only a small amount left for posters.
Better
Predominantly, the budget was spent on supplies, with only a small amount left for posters.
Mainly (formal)
Nuance: Primary reason
Formal; common in reports.
Boring
Mostly, the team chose option B because it was cheaper, not because it was easier.
Better
Primarily, the team chose option B because it was cheaper, not because it was easier.