It’s single digits in some states, but all it takes to end up with nothing is for the owner to notice you and file eviction one day before the end of the period. Actively hiding from the owner also invalidates an adverse possession claim.
The main point of adverse possession isn’t squatters. It’s to give you or your descendants good title after a certain amount of time. There’s a bunch of reasons you can end up with imperfect title even if you think you validly bought or were gifted your property. Adverse possession clears up your title once enough time passes as long as you actually use the land and no one comes along and tries to assert their right.
It is reasonable if you understand the spirit of the law. It was not made to re-distribute land or property; but rather for land or property whose owners have "vanished" or have no more interest in that property (by even giving it away).
Actually the main reason is to limit claims of fraudulent transfer.
If adverse possession is 10 years in your state, you don't need to worry about the seller's grandchildren suing you claiming that you defrauded their ancestors when you bought your land from them. This also acts as a backstop for title insurance: title insurers are essentially off the hook for policies older than the adverse possession time.
The main goal of adverse possession has always been to protect people who bought the land from ancient+stale claims that they bought it through fraud or bought it from somebody who wrongfully claimed they owned it. Otherwise you'd have to keep documentation and proof for all eternity. At some point it has to be okay to no longer have evidence and documentation beyond what's in the public record. Torrens title systems don't change this: the point is to prevent egregiously stale claims of fraud. Fraud is the explicit exceptions to Torrens indefeasibility.
The much-publicized "squatters got free land" phenomenon is just a side effect.
A guy built a castle, and hid it for four years behind straw bales - on the basis that if nobody complained for four years he'd be able to keep it. It didn't work out that way, and he had to demolish it:
The main point of adverse possession isn’t squatters. It’s to give you or your descendants good title after a certain amount of time. There’s a bunch of reasons you can end up with imperfect title even if you think you validly bought or were gifted your property. Adverse possession clears up your title once enough time passes as long as you actually use the land and no one comes along and tries to assert their right.