Some of them are “points-based” and you can spend your points at different resorts that they own and hypothetically have some flexibility in time but “points” should be a bad smell, see

https://en.wikipedia.org/wiki/Razzle_(game)

Where they actually cheat to help you get enough points that you think you could win them when they stop cheating the game is unwinnable. If the cops show up they will see the carnie playing ‘honestly’ and not see anything wrong. In terms of psychology it is the king of scams.

In the case of the timeshare schemes you will find all sorts of problems and limitations when you try to redeem your points, it is like the limitations on airline frequent flier points but raised to the Nth power.

They cover that in their sales pitch. There's supposedly a market for trading timeshares, so you can trade in your timeshare for someone else's, specially if you have a highly coveted one

Of course none of it is as easy as they make it sound.

It’s pretty sweet if you’re on the west coast and you have young kids. Extremely high chance of a good, relaxing time for everyone, and it’s a non stop flight for most people. Plus, many people take multiple vacations in a year.

Obviously, not every worth buying a timeshare.

Idk, as a canadian, going to a tropical island twice a year in the middle of winter sounds pretty nice, even if its the same island.