Let’s see if I can help.
I would imagine that the architect would want to pursue the office building project. This project type is likely more similar in scope and scale to the apartment building projects they have experience with. In addition, a Business occupancy is less risky than a Residential occupancy.
A bank may have security and other requirements the architect is not familiar with. A bank is also likely to be smaller in scale than their typical apartment projects.
A Lab building will be a higher risk occupancy than the architect is used to. There will almost certainly be requirements and regulations that they are not familiar with.
Single family homes are not regulated by the IBC. They are regulated by the IRC (International Residential Code) typically, so they do not have an occupancy group as defined by the IBC. If you’re interested in checking out the scope of buildings covered by the IRC you can read about it at the link below:
Hope this helps!