Pricing up "Are some slots better than others?" starts with the stake per spin. Penny slots and progressive jackpots sit at opposite ends of the same machines. One promises a small stake, the other a huge prize, and both are less simple than they look. What a penny slot really costs per spin, how a jackpot meter grows and what the odds of hitting it are decide whether either is worth playing, and neither rewards a strategy the way their fans hope.
Progressive jackpot strategy mostly means knowing when a game is worth playing at all. Some players use a tracker that records jackpot sizes over time, or a calculator that estimates when a growing prize lifts a game's return above its usual level. Casino jackpot strategies of this kind can point to a better moment, but they cannot change the odds of a single spin, and chasing a big meter with money meant for other things is how sessions go wrong.
Progressive jackpots work by taking a small share of every stake and adding it to a prize that keeps growing until someone wins it. The jackpot meter on the screen shows that running total, and on networked games it rises with stakes from many casinos at once. A mystery progressive jackpot is paid at a random moment before the meter reaches a hidden limit rather than on a symbol combination, so any spin may trigger it.
Rarely. The coin is a penny, but the stake per spin is the coin times the lines times the bet level, which often comes to far more.
On some machines only the maximum stake qualifies, or it raises the chance; the rule is in the game's help screen.
They show meter levels and history, which says something about when a mystery jackpot is near its limit, but nothing about ordinary progressives.
A small share of every stake on the linked machines feeds the meter until someone wins it, then it resets to a seed amount.