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 known.
Free spins expire, often within a day or a few days of being credited, and unused spins simply disappear. Larger offers are frequently released in daily batches, each needing a login or a fresh opt in, so missing a day can mean missing a batch. The winnings from the spins then have their own deadline for wagering. Noting both dates when the spins arrive keeps an offer from lapsing unnoticed in the middle of a busy week.
The value of an offer is the number of spins multiplied by the stake of each spin. A hundred spins at the lowest stake can be worth less than twenty spins at a higher one. Multiplying that total by the return of the eligible slot gives the amount the spins are expected to pay back on average, which is usually a small fraction of the headline impression. The stake per spin is stated in the terms, sometimes only as a coin size.
Winnings from free spins usually arrive as bonus funds with their own wagering requirement, often counted on the winnings alone. Some offers pay spin winnings as cash with no wagering at all, and those offers tend to give fewer spins. A requirement on small winnings can still take a long session to clear, and the balance may run out first. The terms state which of the two applies, usually in the line that describes the spins.
Larger offers are often split by day, each batch needing a login or fresh opt in, so a missed day can mean a lost batch.
Usually as bonus funds with their own wagering, though some offers pay spin winnings straight into the cash balance.
Often yes, frequently counted on the winnings alone, and even a small requirement can take a long session while the balance runs down.
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.