In the windows app a plan time can be set from 00:00 to 24:00, but in the android app there is no option to set 24:00, only 23:59.
It is also a complicated way of setting if you simply want to block an app or a website entirely. It could be a simple option to put a checkmark to “all day”, so no time has to be set up.
There could also be an option (e.g. a checkmark) e.g. to block a website or an app permanently, so no plan/session schedule has to be set up. There could be a separate list of apps/websites that are simply not allowed indefinitely (until removed from the list)