For policies like this, your company culture and the examples leadership sets are going to dictate exactly how something like this, or anything else not explicit, is followed. If leadership often takes vacation and doesn't do more than basic email checking, if that, then employees will feel comfortable doing the same and enjoy this policy over your standard "you accumulate 5 hours of PTO per pay period." If leadershi…
It's about the size of the company and quality of the communication between the management and team. If your dialogue was better with the CEO then you wouldn't feel that way or just ask him/her easily.
In a small company, there are rarely such neatly demarcated lines. Regardless of how well you communicate with your boss about arranging to be done earlier, you will feel the eyes of your coworkers when you head out the door.
edit: A notable exception being results-focused cultures that emphasize flexibility as a company value. If punching the clock is an expectation, it's hard to manage to be on a shifted schedule without there being at least a twinge of resentment when you head out earlier.