Originally posted by Black bolt z
He used all the gems when fighting the cosmics.
Individually.
When he reversed Chrono's time manipulation, that was the time gem at work. When he blasted the Celestials into atoms, that was the power gem.
Just because he didn't state which gem he was using, like Warlock did against Strange, doesn't mean he was somehow using all the gems in unison for each effect. Each gem has a specific power, and that's how you can tell he's only accessing one at a time..