I will saddle soap if my tack is dirty. But I actually consider oiling more important. So I do a very basic cleaning and then condition, usually with neatsfoot oil. I also love Leather Therapy Conditioner and Skidmore's Leather Cream. But those products are more expensive than neatsfoot so I usually condition with neatsfoot oil.
I probably do my saddles about 2-3 times a year (more frequently if I am breaking a saddle in) and bridles maybe once a year.
I have also heard of using a finishing layer of saddle soap for protection but then I have also heard that it is not good to clog the pores. So lately I have been oiling without the finishing saddle soap layer. My tack has done just fine this way for years and years. I would much rather have supple leather that bends than dry leather that cracks. I live in Arizona though and it almost seems like you cannot over oil anything!
When I was a beginner I enjoyed oiling my tack and probably over oiled but the only thing I ever ruined was some saddle bags made from a cheap suede type leather. I never had any quality leather break down from heavy oiling even when I was young and dumb.