Or bank any leave at all. My current employer wipes vacation days on Jan 1.

My experience with employers in general is use any benefit you accrue as soon as you reasonably can. Don't save stuff up; it makes you vulnerable to your employers incompetence or greed.

This. Also, flexible sick days(ie, "unlimited").. it works out nice for when you get the flu or whatever and don't have to worry about how many sick days you burn, but a major event like this doesn't really apply and you'll end up needing to burn vacation days or take unpaid leave to recover, not to mention wanting any bonding time

My last two places were like this. I can't say I was happy about changing, but I can say I priced it into the equation.

In some places, that policy is in place to encourage employees to actually take time off. If it wasn't use-it-or-lose-it, some people would never take leave.

We always hear this, but it doesn't really make sense. First, a firm that actually wanted employees to take vacation could just make a policy by which a certain percentage of banked time would be automatically scheduled by HR after so long a period of banking. Second, under the "lose-it" policy, many employees don't actually use all their allotted vacation. This can happen even to those who really try to schedule it. A cynical manager can always stymie the best-considered vacation plans. I consider that this common result is actually the intent of this anti-employee policy. (At many firms; of course any particular firm may be an exception.)

No, it is so the employer doesn't need to carry the additional liability in their accounting. Vacation time is something with a monetary value that must be paid out if the employee is terminated.

Aren't they generally required to pay you for accrued leave or is even that not required?

My employer will not pay us for accrued leave. I saw the end result recently when a co-worker took a week and a half off only to return with his resignation in hand. Guess he cashed out his vacation time anyway....

Now we all realize that if someone is going to resign, it's most likely going to happen after a long vacation. I don't know if HR realizes this yet.

(not a lawyer) I think in the US (oops, probably should have said California) generally accrued vacation has to be paid off (as it is accounted for at the time it is earned, but there may also be a cap which causes some to disappear). But sick days are not generally considered a benefit and avoid this. I imagine "flex time" is more complicated.

Usually depends on which state you are in. California I believe they are required to pay up to a certain number of hours.

In CA leave is vested, it has to be paid out. Not all states have this policy.

In most states, that's not required.