4 cards in 8 hours seems awfully high, I personally have been getting 1 drop every 30 minutes since they removed the mandatory 2 hour before normal drops start.

Idle Master will have the same drop time as actually running the game. Unless you plan on playing the game, there's no advantage to spending the time downloading the game in order to manually idle it.

Some of us still have to put up with 2+ hours until the first card drop so a tool like Idle Master can be quite useful.