When installing a humbucker, it doesn’t really matter the direction you’re installing it, even if you’re installing them backward. While some of them have a really different sound when installed the other way around, they still work. It is ultimately a choice of preference because most humbuckers will sound brighter when installed differently.
Furthermore, when it comes to single-coil models, they are even less sensitive to installation direction. Their magnets are so close together that reversing their direction has no sensitive effect over the sound. Of course, there are some that argue so much that coils should be installed in a certain way, but that’s not true.
On top of it all, there are certain guitars where you can’t really fit the humbucker or the single-coil as you would want and you need to reverse its direction. This could lead to a severe decrease in the sound quality if the direction had any effect, but that’s not the case.