What we have here is some guidelines for fence line heights when installing a permanent electric fence.
The fence heights given are not gospel and you could argue that whatever height works is the right height. There is certainly room for adjustment based on your own preferences and you must always take the size of your individual animals into account.
If you have any doubts at all about the height of fence lines, it is always better to move the suggested lines down a little and then add an additional high line.