The design that business cards tend to use was codified a really long time ago, and it can impact how you would choose to design your own business cards in some way, shape or form. However, it might also serve you relatively well to figure out a situation wherein you can go about modifying this basic design at any given point in time. A big part of the reason why that is the case has to do with the fact that when you opt for something that is a little less run of the mill such as a vertical business card, you would find that it would have the potential to have a bit stronger of an impact if you think about it.
The thing that makes Black Metal Kards that have been designed vertically so special is the fact that they will stand apart from the rest. The basic premise of this is that instead of the information being arrayed in such a way that it can only ever end up being read if you hold the card up horizontally, you would go about using a vertical approach for this type of thing.
If you consider how people tend to hand over business cards and the like, you would notice that this usually happens vertically anyway. It is very uncommon for you to hand it over horizontally, so the thing that vertical design would do is that it would give you the chance to hand the card over to someone and allow them to read everything that is on it without having to worry about them having to first flip it horizontally which can save you a lot of time all in all.