I split into 2 section. 宅气 and 宅体. In the measurement of 宅体, landform belongs to form school. If you have a 逼刀 for example, the likelihood of 凶 happening in the sector will be higher especially on 绝命 and 五鬼. Nonetheless, there are example when there is 逼刀 but owner still ok. One reason Is because of factors such as distance of 逼刀 is and the formation of 气点 relative to the 宅 is rather weak, or if the 宅体 is strong enough to take the 逼刀. By 逼刀， I also mean 路沖 and other aspect form school.
In the event 宅体 cannot be strengthen by external landform, such as the 4 celestial animals, the Qi map become a even important factor. Using the good sectors etc to strengthen 宅气 to withstand the 外煞.
For example, want to assess wealth star, one application can use door as 伏位 and plot out the qi map for Fu xin water and interlay with the qi map for assess. For actual mountain such as 贪狼山，武曲山 etc. I live in the city, so didn’t dwell much into this aspect of landform.
I work more with the idea of also split 8 mansion into 24 mountain if I need to work with placement. Of cos many of the classical Feng Shui will say they are classical and don’t use placement and energy items, so to each his own in this aspect. In 八宅明镜 this book, it advocated that stove is place in Inauspicious Sector and to face it toward auspicious, in my opinion is one indication of placement in Feng Shui.