The more time you spend in one day, the more rewards are claimable:

Time: Reward:
5minutes 1 Silver Coin Card
10minutes 1 Exp Card
15minutes 1 Stamina Card
30minutes 1 Magic Crystal Card & Silver Coin Card
1 Hour 2 Silver Coin Cards & 1 Stamina Card
2 Hours 1 Reputation Card & 5 Silver Coin Card
3 Hours 1 Tower of Paradise Card 1 Reputation Card and 1 Stamina Card
7 Hours (total) for all Rewards Must be online, to claim them and be aware.

Trick: Download an auto-clicker and make sure your internet connection is working well. You can then just stay in the same place with the mouse and claim the gifts by auto-clicking the "claim"-button. ;)