I have great coverage that included rental income loss, but I still had to come up with the unit in a quad.

Different types of coverages or anything like that? 

This covers the property in case of damage from natural causes, usually has coverage if the renter damages the property or it is damaged by vandals, and also contains liability if the tenant or someone else slips and falls and sues you as the property owner. 

The nice thing about using that company is that you pay by the month rather than say by the quarter; consider that companies offering this type of coverage typically consider the entire premium earned even if you cancel before the end of the term (i.e. no refunds when you cancel early). 

Insurers usually have a core competence and Jason's great at matching that up to get the best coverage at the lowest amount.  

But then I also found a more comprehensive blog post by J Scott so I'll try to redo my spreadsheet using his formulas.

I own an apartment complex and every year I have the option of adding terrorism insurance to my coverage.

Could be suspicious, but if you get title insurance coverage, I don't think you need to worry about it. 

I understand that I will not have a full comprehensive understanding of all the interworking as I haven't contacted the seller to negotiate any deals.  

If so: yes, I had more coverage per incident.