The gist of "Are free spins worth it?" is simple: spins are worth less than they look. Free spins are the most common casino offer and the hardest to value at a glance. Each spin has a fixed stake set by the casino, often the smallest the game allows, and the winnings may land as cash or as a bonus with wagering. The number of spins in the headline says little until the spin value, the eligible games and the terms on winnings are clear.
Spins are tied to one slot or a short list of them, chosen by the casino. The eligible game decides both the return and the volatility of the offer: spins on a volatile slot mostly pay nothing and occasionally pay well, while spins on a steady one return small amounts more reliably. The game is named in the offer, and its return can be checked in its help screen before the spins are claimed.
A cap on free spin winnings limits how much the spins can turn into, however well they land. Anything above the cap is removed when the bonus converts to cash. Caps are common on spins given without a deposit and can be low enough to make a large hit on the eligible slot pointless. The figure is part of the offer terms and matters most on volatile games, where the rare big result is the whole point of playing.
Paying spin winnings as cash with no wagering costs the casino more per spin, so those offers tend to include a smaller number of spins.
Multiply the number of spins by the stake of each spin; a hundred spins at the lowest stake can be worth less than twenty at a higher one.
Often a day or a few days after being credited, and any spins left unused simply disappear from the account.
The casino ties spins to one slot or a short list, named in the offer, and that game sets both the return and the volatility.
The casino fixes it in the offer terms, often at the smallest stake the game allows, sometimes stating it only as a coin value.
Usually as bonus funds with their own wagering, though some offers pay spin winnings straight into the cash balance.