Do You Use Decans? Why?

Hello, Everyone

I am curious if some people use Decans when reading a chart, i am not just considering the "Sun Sign" which limitlessly known and most likely used by people.

I know some use decans but it's small and i want to know if you do or not?

Ex.

Pisces Venus "15, 13 Degree", 2nd Decan, Neptune - Moon (Pisces and Cancer) 0 - 19 Degrees

Because if you do, do you use Modern or Traditional Rulerships? 

I use Modern completely, all placements major minor asteroid etc., Earth is considered and is under Taurus cause this world deserve to be part of astrology. "Positioned opposite of the Sun"