It doesn’t really take more than an hour.
To play just to earn daily, 30 minutes is okay.
But if you join tournaments and brawls you play on intervals.
Then there is daily quest which you would want to complete to gain daily rewards.
Also you can hire somebody to play your account and share the spoils with them.
Season ends every two weeks, you will still get rewards depending on league you finished for the season.
But the key to earn higher is to invest to accumulate collection power just like hive power.