Yes,exactly.The phone will automatically adjust the battery life according to your preference of power consumption.
For more tips,you could take a read at this
/t5/FAQ/Battery-time-and-enhancement-features/m-p/347874#U347874One tip,i heard that if you want to charge phones quickly,its better to swich to airplane mode rather than switching it off.
I never really tested it yet though
Cheers too !