From an article about a Broadway brouhaha:
"... We found the few good things people had said, stood by her, and kept going. The critics were not wrong, but we tried
to major on (her) sweetness and innocence..."

"to major on"
In a university or college you can
major in a subject. Obviously that is a completely different context.
And so, what is wrong with "we tried
to focus on (or upon)..." ?
Broadway slang of some sort? If so, it fails our tests of wit and nuance!
