Bad management "not getting" the request for time off has played havoc on my free time in the past.
This is exactly why I’m very happy my current employers went to computerized scheduling including time off submissions. If you didn’t ask for the time off early enough and keep checking on it to make sure you were approved (or work something else out if you weren’t) it’s your fault.
Now, if you submit the request and it IS approved but you get scheduled anyway (which is extremely rare now) most reasonable managers will work it out. So you don’t have to work and you don’t end up with any attendance issues.
Of course, key phrase os "reasonable managers."