Slot machines feature many types of symbols: bars, 7s, double diamonds, cherries, double bars, etc. Bars aren't more important than cherries and 7s aren't less important than double diamonds. The point is that focusing on these symbols is useless. Players had better focus on other aspects, such as the reels. The higher the number of reels, the more difficult it will be to hit the jackpot. The same goes for winning various combinations.
Take the following example: you have to line up 3 double diamonds on 1 pay line in order to hit the jackpot. Knowing that each reel will have one double diamond on it, these are the chances of lining up 3 double diamonds on a 3 reel machine. Add one more detail: each reel has 18 symbols:
- 5832 possible combinations of symbols on all of the 3 reels: 18 x 18 x18 > 5832
- The odds of hitting 3 double diamonds on 3 reels are 1 in 5832 (1/5832)
Knowing this, imagine how hard it is to hit the jackpot on a 5 reel machine: 1 in 1.889.568 > 1/ (18x18x18x18x18)
All things considered, it is only the number of reels and symbols that can affect the outcome of the game. The more symbols /reels, the smaller your chances of hitting a winning combination.