The phrase "I mostly spend" is grammatically correct and can be used in written English.
Example: "I mostly spend my weekends hiking in the mountains." In this sentence, "I mostly spend" indicates that the majority of the speaker's time on weekends is dedicated to hiking in the mountains.
"On playgrounds, I mostly spend my time having imaginary arguments with other parents who are secretly judging me," the singer Jonathan Coulton, a Brooklyn parent, recently posted on Twitter.
"I'm thinking about a philanthropy strategy that is the opposite of how I mostly spend my time -- working on the long term," he wrote.
Victoria: I mostly spend my time exploring the streets of New York City with my friends.
West Los Angeles falls somewhere between my two other residences, but in LA, aside from shows at the Geffen Playhouse and Hollywood Improv, I mostly spend time with my parents.
I mostly spend time with Sheri who is teaching me to sew.
I trust readers will understand that by "visiting the worlds of writers and exploring sites of the Republican cause," I mean I mostly spent it pub-crawling.
I mostly spent the summer working as a pool boy at condos and Trump Tower though, just to even things out.
I was never allowed to trick-or-treat as a kid, so I mostly spent Halloween watching spooky movies by myself.
I mostly spent my time writing poetry that was straight-up just terrible Morrissey and Isaac Brock lyrical rip-off, and trying to avoid getting diarrhea in Geometry and shitting my pants.
Toward the end of the trip's final day, which I'd mostly spent at the bridge table while hundreds of potentially interesting seabirds wheeled around outside, I went down to the lounge for a lecture on climate change.
The 1980s were a dull decade for him, mostly spent directing chamber films based on small-cast, one-set plays.
