The schedules are what you ask for. Normally you get 9 days off, then you can add 2 of your annual 24 vacation days and get 11 days off in a row. You then get 3 total travel days. All in all, you are home 13 days a month if you include the day you arrive home and the day you leave. Whatever block of days you ask off, 99.99% of the time you get those exact days. US Holidays has not been an issue at all. It's usually the two Korean holidays in FEB and SEP, that they 'request' we work, which doesn't conflict with any US holidays.
Now, for some aircraft you can do an Option program which allows you to split up your days and be home based at your base. For the US, the only base that became available starting in April was in Vegas for the A330. This is a nice deal since the ideal schedule is week on/ week off and so on. Instead of being charged 7 days off, you are only charged 5. That's important because you will average being home for 16 days and only get charged the normal 11 days. 3 days of travel, so that gives you two free days a month and you leave in shorter intervals. the downside of the option program is that you cannot ask for what days you want off. Once you are start a cycle of days on/off, you just keep doing it, until you ask to go back to a normal schedule which you can do at any month. Most of us will go back to a normal schedule come NOV and DEC so we can get the holidays off. Then come JAN we'll probably go back to the Option program. Korean is the best for getting your days off, compared to any other foreign airlines. Hope that helps.