Usage patterns
次第に〜になるto gradually become ~
The sky gradually became dark.
次第に〈動詞〉てくるto gradually start ~ing (change approaching the speaker)
I gradually started to understand what he was saying.
次第に増える/減るto gradually increase / decrease
The population is gradually decreasing.
次第に〜に慣れるto gradually get used to ~
I gradually got used to my new life.
Expressions
事と次第によってはdepending on the circumstances; if the situation calls for it